diff --git a/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline b/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline
index 878cdeb02..dea4863c4 100644
--- a/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline
+++ b/baselines/bigquery-storage/src/v1beta1/big_query_storage_client.ts.baseline
@@ -37,8 +37,13 @@ export class BigQueryStorageClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  bigQueryStorageStub: Promise<{[name: string]: Function}>;
+  bigQueryStorageStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of BigQueryStorageClient.
@@ -91,28 +96,31 @@ export class BigQueryStorageClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof BigQueryStorageClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -122,7 +130,7 @@ export class BigQueryStorageClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -132,10 +140,10 @@ export class BigQueryStorageClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      readSessionPathTemplate: new gaxModule.PathTemplate(
+      readSessionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/locations/{location}/sessions/{session}'
       ),
-      streamPathTemplate: new gaxModule.PathTemplate(
+      streamPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/locations/{location}/streams/{stream}'
       ),
     };
@@ -143,11 +151,11 @@ export class BigQueryStorageClient {
     // Some of the methods on this service provide streaming responses.
     // Provide descriptors for these.
     this._descriptors.stream = {
-      readRows: new gaxModule.StreamDescriptor(gax.StreamType.SERVER_STREAMING)
+      readRows: new this._gaxModule.StreamDescriptor(gax.StreamType.SERVER_STREAMING)
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.cloud.bigquery.storage.v1beta1.BigQueryStorage', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -155,15 +163,33 @@ export class BigQueryStorageClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.bigQueryStorageStub) {
+      return this.bigQueryStorageStub;
+    }
 
     // Put together the "service stub" for
     // google.cloud.bigquery.storage.v1beta1.BigQueryStorage.
-    this.bigQueryStorageStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.cloud.bigquery.storage.v1beta1.BigQueryStorage') :
+    this.bigQueryStorageStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.cloud.bigquery.storage.v1beta1.BigQueryStorage') :
           // tslint:disable-next-line no-any
-          (protos as any).google.cloud.bigquery.storage.v1beta1.BigQueryStorage,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.cloud.bigquery.storage.v1beta1.BigQueryStorage,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -182,9 +208,9 @@ export class BigQueryStorageClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -198,6 +224,8 @@ export class BigQueryStorageClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.bigQueryStorageStub;
   }
 
   /**
@@ -343,6 +371,7 @@ export class BigQueryStorageClient {
       'table_reference.project_id': request.tableReference!.projectId || '',
       'table_reference.dataset_id': request.tableReference!.datasetId || '',
     });
+    this.initialize();
     return this._innerApiCalls.createReadSession(request, options, callback);
   }
   batchCreateReadSessionStreams(
@@ -409,6 +438,7 @@ export class BigQueryStorageClient {
     ] = gax.routingHeader.fromParams({
       'session.name': request.session!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.batchCreateReadSessionStreams(request, options, callback);
   }
   finalizeStream(
@@ -481,6 +511,7 @@ export class BigQueryStorageClient {
     ] = gax.routingHeader.fromParams({
       'stream.name': request.stream!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.finalizeStream(request, options, callback);
   }
   splitReadStream(
@@ -560,6 +591,7 @@ export class BigQueryStorageClient {
     ] = gax.routingHeader.fromParams({
       'original_stream.name': request.originalStream!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.splitReadStream(request, options, callback);
   }
 
@@ -598,6 +630,7 @@ export class BigQueryStorageClient {
     ] = gax.routingHeader.fromParams({
       'read_position.stream.name': request.readPosition!.stream!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.readRows(request, options);
   }
 
@@ -709,8 +742,9 @@ export class BigQueryStorageClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.bigQueryStorageStub.then(stub => {
+      return this.bigQueryStorageStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/bigquery-storage/test/gapic-big_query_storage-v1beta1.ts.baseline b/baselines/bigquery-storage/test/gapic-big_query_storage-v1beta1.ts.baseline
index f21cc6581..7d9f3e076 100644
--- a/baselines/bigquery-storage/test/gapic-big_query_storage-v1beta1.ts.baseline
+++ b/baselines/bigquery-storage/test/gapic-big_query_storage-v1beta1.ts.baseline
@@ -97,12 +97,30 @@ describe('v1beta1.BigQueryStorageClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new bigquerystorageModule.v1beta1.BigQueryStorageClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.bigQueryStorageStub, undefined);
+        await client.initialize();
+        assert(client.bigQueryStorageStub);
+    });
+    it('has close method', () => {
+        const client = new bigquerystorageModule.v1beta1.BigQueryStorageClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('createReadSession', () => {
         it('invokes createReadSession without error', done => {
             const client = new bigquerystorageModule.v1beta1.BigQueryStorageClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.ICreateReadSessionRequest = {};
             request.tableReference = {};
@@ -129,6 +147,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.ICreateReadSessionRequest = {};
             request.tableReference = {};
@@ -157,6 +177,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.IBatchCreateReadSessionStreamsRequest = {};
             request.session = {};
@@ -181,6 +203,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.IBatchCreateReadSessionStreamsRequest = {};
             request.session = {};
@@ -207,6 +231,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.IFinalizeStreamRequest = {};
             request.stream = {};
@@ -231,6 +257,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.IFinalizeStreamRequest = {};
             request.stream = {};
@@ -257,6 +285,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.ISplitReadStreamRequest = {};
             request.originalStream = {};
@@ -281,6 +311,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.ISplitReadStreamRequest = {};
             request.originalStream = {};
@@ -307,6 +339,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.IReadRowsRequest = {};
             request.readPosition = {};
@@ -331,6 +365,8 @@ describe('v1beta1.BigQueryStorageClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.bigquery.storage.v1beta1.IReadRowsRequest = {};
             request.readPosition = {};
diff --git a/baselines/dlp/src/v2/dlp_service_client.ts.baseline b/baselines/dlp/src/v2/dlp_service_client.ts.baseline
index 4590b416b..9f8d0bbd7 100644
--- a/baselines/dlp/src/v2/dlp_service_client.ts.baseline
+++ b/baselines/dlp/src/v2/dlp_service_client.ts.baseline
@@ -44,8 +44,13 @@ export class DlpServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  dlpServiceStub: Promise<{[name: string]: Function}>;
+  dlpServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of DlpServiceClient.
@@ -98,28 +103,31 @@ export class DlpServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof DlpServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -129,7 +137,7 @@ export class DlpServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -139,34 +147,34 @@ export class DlpServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      dlpJobPathTemplate: new gaxModule.PathTemplate(
+      dlpJobPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/dlpJobs/{dlp_job}'
       ),
-      jobTriggerPathTemplate: new gaxModule.PathTemplate(
+      jobTriggerPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/jobTriggers/{job_trigger}'
       ),
-      organizationPathTemplate: new gaxModule.PathTemplate(
+      organizationPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}'
       ),
-      organizationDeidentifyTemplatePathTemplate: new gaxModule.PathTemplate(
+      organizationDeidentifyTemplatePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/deidentifyTemplates/{deidentify_template}'
       ),
-      organizationInspectTemplatePathTemplate: new gaxModule.PathTemplate(
+      organizationInspectTemplatePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/inspectTemplates/{inspect_template}'
       ),
-      organizationStoredInfoTypePathTemplate: new gaxModule.PathTemplate(
+      organizationStoredInfoTypePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/storedInfoTypes/{stored_info_type}'
       ),
-      projectPathTemplate: new gaxModule.PathTemplate(
+      projectPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}'
       ),
-      projectDeidentifyTemplatePathTemplate: new gaxModule.PathTemplate(
+      projectDeidentifyTemplatePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/deidentifyTemplates/{deidentify_template}'
       ),
-      projectInspectTemplatePathTemplate: new gaxModule.PathTemplate(
+      projectInspectTemplatePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/inspectTemplates/{inspect_template}'
       ),
-      projectStoredInfoTypePathTemplate: new gaxModule.PathTemplate(
+      projectStoredInfoTypePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/storedInfoTypes/{stored_info_type}'
       ),
     };
@@ -176,19 +184,19 @@ export class DlpServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listInspectTemplates:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'inspectTemplates'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'inspectTemplates'),
       listDeidentifyTemplates:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'deidentifyTemplates'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'deidentifyTemplates'),
       listJobTriggers:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'jobTriggers'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'jobTriggers'),
       listDlpJobs:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'jobs'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'jobs'),
       listStoredInfoTypes:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'storedInfoTypes')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'storedInfoTypes')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.privacy.dlp.v2.DlpService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -196,15 +204,33 @@ export class DlpServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.dlpServiceStub) {
+      return this.dlpServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.privacy.dlp.v2.DlpService.
-    this.dlpServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.privacy.dlp.v2.DlpService') :
+    this.dlpServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.privacy.dlp.v2.DlpService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.privacy.dlp.v2.DlpService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.privacy.dlp.v2.DlpService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -223,9 +249,9 @@ export class DlpServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -239,6 +265,8 @@ export class DlpServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.dlpServiceStub;
   }
 
   /**
@@ -371,6 +399,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.inspectContent(request, options, callback);
   }
   redactImage(
@@ -449,6 +478,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.redactImage(request, options, callback);
   }
   deidentifyContent(
@@ -540,6 +570,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.deidentifyContent(request, options, callback);
   }
   reidentifyContent(
@@ -633,6 +664,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.reidentifyContent(request, options, callback);
   }
   listInfoTypes(
@@ -695,6 +727,7 @@ export class DlpServiceClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.listInfoTypes(request, options, callback);
   }
   createInspectTemplate(
@@ -767,6 +800,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createInspectTemplate(request, options, callback);
   }
   updateInspectTemplate(
@@ -833,6 +867,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateInspectTemplate(request, options, callback);
   }
   getInspectTemplate(
@@ -895,6 +930,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getInspectTemplate(request, options, callback);
   }
   deleteInspectTemplate(
@@ -957,6 +993,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteInspectTemplate(request, options, callback);
   }
   createDeidentifyTemplate(
@@ -1030,6 +1067,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createDeidentifyTemplate(request, options, callback);
   }
   updateDeidentifyTemplate(
@@ -1097,6 +1135,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateDeidentifyTemplate(request, options, callback);
   }
   getDeidentifyTemplate(
@@ -1160,6 +1199,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getDeidentifyTemplate(request, options, callback);
   }
   deleteDeidentifyTemplate(
@@ -1223,6 +1263,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteDeidentifyTemplate(request, options, callback);
   }
   createJobTrigger(
@@ -1294,6 +1335,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createJobTrigger(request, options, callback);
   }
   updateJobTrigger(
@@ -1359,6 +1401,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateJobTrigger(request, options, callback);
   }
   getJobTrigger(
@@ -1420,6 +1463,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getJobTrigger(request, options, callback);
   }
   deleteJobTrigger(
@@ -1481,6 +1525,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteJobTrigger(request, options, callback);
   }
   activateJobTrigger(
@@ -1542,6 +1587,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.activateJobTrigger(request, options, callback);
   }
   createDlpJob(
@@ -1619,6 +1665,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createDlpJob(request, options, callback);
   }
   getDlpJob(
@@ -1680,6 +1727,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getDlpJob(request, options, callback);
   }
   deleteDlpJob(
@@ -1743,6 +1791,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteDlpJob(request, options, callback);
   }
   cancelDlpJob(
@@ -1806,6 +1855,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.cancelDlpJob(request, options, callback);
   }
   createStoredInfoType(
@@ -1878,6 +1928,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createStoredInfoType(request, options, callback);
   }
   updateStoredInfoType(
@@ -1948,6 +1999,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateStoredInfoType(request, options, callback);
   }
   getStoredInfoType(
@@ -2011,6 +2063,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getStoredInfoType(request, options, callback);
   }
   deleteStoredInfoType(
@@ -2074,6 +2127,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteStoredInfoType(request, options, callback);
   }
 
@@ -2174,6 +2228,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listInspectTemplates(request, options, callback);
   }
 
@@ -2237,6 +2292,7 @@ export class DlpServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listInspectTemplates.createStream(
       this._innerApiCalls.listInspectTemplates as gax.GaxCall,
       request,
@@ -2341,6 +2397,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listDeidentifyTemplates(request, options, callback);
   }
 
@@ -2404,6 +2461,7 @@ export class DlpServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listDeidentifyTemplates.createStream(
       this._innerApiCalls.listDeidentifyTemplates as gax.GaxCall,
       request,
@@ -2533,6 +2591,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listJobTriggers(request, options, callback);
   }
 
@@ -2622,6 +2681,7 @@ export class DlpServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listJobTriggers.createStream(
       this._innerApiCalls.listJobTriggers as gax.GaxCall,
       request,
@@ -2754,6 +2814,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listDlpJobs(request, options, callback);
   }
 
@@ -2845,6 +2906,7 @@ export class DlpServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listDlpJobs.createStream(
       this._innerApiCalls.listDlpJobs as gax.GaxCall,
       request,
@@ -2950,6 +3012,7 @@ export class DlpServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listStoredInfoTypes(request, options, callback);
   }
 
@@ -3014,6 +3077,7 @@ export class DlpServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listStoredInfoTypes.createStream(
       this._innerApiCalls.listStoredInfoTypes as gax.GaxCall,
       request,
@@ -3364,8 +3428,9 @@ export class DlpServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.dlpServiceStub.then(stub => {
+      return this.dlpServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/dlp/test/gapic-dlp_service-v2.ts.baseline b/baselines/dlp/test/gapic-dlp_service-v2.ts.baseline
index 3d9f65d0e..54c9ad3a0 100644
--- a/baselines/dlp/test/gapic-dlp_service-v2.ts.baseline
+++ b/baselines/dlp/test/gapic-dlp_service-v2.ts.baseline
@@ -78,12 +78,30 @@ describe('v2.DlpServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new dlpserviceModule.v2.DlpServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.dlpServiceStub, undefined);
+        await client.initialize();
+        assert(client.dlpServiceStub);
+    });
+    it('has close method', () => {
+        const client = new dlpserviceModule.v2.DlpServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('inspectContent', () => {
         it('invokes inspectContent without error', done => {
             const client = new dlpserviceModule.v2.DlpServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IInspectContentRequest = {};
             request.parent = '';
@@ -107,6 +125,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IInspectContentRequest = {};
             request.parent = '';
@@ -132,6 +152,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IRedactImageRequest = {};
             request.parent = '';
@@ -155,6 +177,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IRedactImageRequest = {};
             request.parent = '';
@@ -180,6 +204,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeidentifyContentRequest = {};
             request.parent = '';
@@ -203,6 +229,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeidentifyContentRequest = {};
             request.parent = '';
@@ -228,6 +256,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IReidentifyContentRequest = {};
             request.parent = '';
@@ -251,6 +281,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IReidentifyContentRequest = {};
             request.parent = '';
@@ -276,6 +308,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListInfoTypesRequest = {};
             // Mock response
@@ -298,6 +332,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListInfoTypesRequest = {};
             // Mock response
@@ -322,6 +358,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateInspectTemplateRequest = {};
             request.parent = '';
@@ -345,6 +383,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateInspectTemplateRequest = {};
             request.parent = '';
@@ -370,6 +410,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateInspectTemplateRequest = {};
             request.name = '';
@@ -393,6 +435,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateInspectTemplateRequest = {};
             request.name = '';
@@ -418,6 +462,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetInspectTemplateRequest = {};
             request.name = '';
@@ -441,6 +487,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetInspectTemplateRequest = {};
             request.name = '';
@@ -466,6 +514,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteInspectTemplateRequest = {};
             request.name = '';
@@ -489,6 +539,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteInspectTemplateRequest = {};
             request.name = '';
@@ -514,6 +566,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateDeidentifyTemplateRequest = {};
             request.parent = '';
@@ -537,6 +591,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateDeidentifyTemplateRequest = {};
             request.parent = '';
@@ -562,6 +618,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateDeidentifyTemplateRequest = {};
             request.name = '';
@@ -585,6 +643,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateDeidentifyTemplateRequest = {};
             request.name = '';
@@ -610,6 +670,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetDeidentifyTemplateRequest = {};
             request.name = '';
@@ -633,6 +695,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetDeidentifyTemplateRequest = {};
             request.name = '';
@@ -658,6 +722,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteDeidentifyTemplateRequest = {};
             request.name = '';
@@ -681,6 +747,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteDeidentifyTemplateRequest = {};
             request.name = '';
@@ -706,6 +774,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateJobTriggerRequest = {};
             request.parent = '';
@@ -729,6 +799,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateJobTriggerRequest = {};
             request.parent = '';
@@ -754,6 +826,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateJobTriggerRequest = {};
             request.name = '';
@@ -777,6 +851,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateJobTriggerRequest = {};
             request.name = '';
@@ -802,6 +878,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetJobTriggerRequest = {};
             request.name = '';
@@ -825,6 +903,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetJobTriggerRequest = {};
             request.name = '';
@@ -850,6 +930,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteJobTriggerRequest = {};
             request.name = '';
@@ -873,6 +955,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteJobTriggerRequest = {};
             request.name = '';
@@ -898,6 +982,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IActivateJobTriggerRequest = {};
             request.name = '';
@@ -921,6 +1007,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IActivateJobTriggerRequest = {};
             request.name = '';
@@ -946,6 +1034,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateDlpJobRequest = {};
             request.parent = '';
@@ -969,6 +1059,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateDlpJobRequest = {};
             request.parent = '';
@@ -994,6 +1086,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetDlpJobRequest = {};
             request.name = '';
@@ -1017,6 +1111,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetDlpJobRequest = {};
             request.name = '';
@@ -1042,6 +1138,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteDlpJobRequest = {};
             request.name = '';
@@ -1065,6 +1163,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteDlpJobRequest = {};
             request.name = '';
@@ -1090,6 +1190,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICancelDlpJobRequest = {};
             request.name = '';
@@ -1113,6 +1215,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICancelDlpJobRequest = {};
             request.name = '';
@@ -1138,6 +1242,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateStoredInfoTypeRequest = {};
             request.parent = '';
@@ -1161,6 +1267,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.ICreateStoredInfoTypeRequest = {};
             request.parent = '';
@@ -1186,6 +1294,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateStoredInfoTypeRequest = {};
             request.name = '';
@@ -1209,6 +1319,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IUpdateStoredInfoTypeRequest = {};
             request.name = '';
@@ -1234,6 +1346,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetStoredInfoTypeRequest = {};
             request.name = '';
@@ -1257,6 +1371,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IGetStoredInfoTypeRequest = {};
             request.name = '';
@@ -1282,6 +1398,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteStoredInfoTypeRequest = {};
             request.name = '';
@@ -1305,6 +1423,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IDeleteStoredInfoTypeRequest = {};
             request.name = '';
@@ -1330,6 +1450,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListInspectTemplatesRequest = {};
             request.parent = '';
@@ -1353,6 +1475,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListInspectTemplatesRequest = {};
             request.parent = '';
@@ -1378,6 +1502,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListDeidentifyTemplatesRequest = {};
             request.parent = '';
@@ -1401,6 +1527,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListDeidentifyTemplatesRequest = {};
             request.parent = '';
@@ -1426,6 +1554,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListJobTriggersRequest = {};
             request.parent = '';
@@ -1449,6 +1579,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListJobTriggersRequest = {};
             request.parent = '';
@@ -1474,6 +1606,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListDlpJobsRequest = {};
             request.parent = '';
@@ -1497,6 +1631,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListDlpJobsRequest = {};
             request.parent = '';
@@ -1522,6 +1658,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListStoredInfoTypesRequest = {};
             request.parent = '';
@@ -1545,6 +1683,8 @@ describe('v2.DlpServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.privacy.dlp.v2.IListStoredInfoTypesRequest = {};
             request.parent = '';
diff --git a/baselines/kms/src/v1/key_management_service_client.ts.baseline b/baselines/kms/src/v1/key_management_service_client.ts.baseline
index 1a92dc14c..43533120f 100644
--- a/baselines/kms/src/v1/key_management_service_client.ts.baseline
+++ b/baselines/kms/src/v1/key_management_service_client.ts.baseline
@@ -45,8 +45,13 @@ export class KeyManagementServiceClient {
   private _descriptors: Descriptors = {page: {}, stream: {}, longrunning: {}};
   private _innerApiCalls: {[name: string]: Function};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  keyManagementServiceStub: Promise<{[name: string]: Function}>;
+  keyManagementServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of KeyManagementServiceClient.
@@ -99,28 +104,31 @@ export class KeyManagementServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof KeyManagementServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -130,7 +138,7 @@ export class KeyManagementServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -141,17 +149,17 @@ export class KeyManagementServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listKeyRings:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'keyRings'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'keyRings'),
       listCryptoKeys:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'cryptoKeys'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'cryptoKeys'),
       listCryptoKeyVersions:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'cryptoKeyVersions'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'cryptoKeyVersions'),
       listImportJobs:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'importJobs')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'importJobs')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.cloud.kms.v1.KeyManagementService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -159,15 +167,33 @@ export class KeyManagementServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.keyManagementServiceStub) {
+      return this.keyManagementServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.cloud.kms.v1.KeyManagementService.
-    this.keyManagementServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.cloud.kms.v1.KeyManagementService') :
+    this.keyManagementServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.cloud.kms.v1.KeyManagementService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.cloud.kms.v1.KeyManagementService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.cloud.kms.v1.KeyManagementService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -186,9 +212,9 @@ export class KeyManagementServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -202,6 +228,8 @@ export class KeyManagementServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.keyManagementServiceStub;
   }
 
   /**
@@ -313,6 +341,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getKeyRing(request, options, callback);
   }
   getCryptoKey(
@@ -373,6 +402,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getCryptoKey(request, options, callback);
   }
   getCryptoKeyVersion(
@@ -432,6 +462,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getCryptoKeyVersion(request, options, callback);
   }
   getPublicKey(
@@ -495,6 +526,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getPublicKey(request, options, callback);
   }
   getImportJob(
@@ -554,6 +586,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getImportJob(request, options, callback);
   }
   createKeyRing(
@@ -619,6 +652,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createKeyRing(request, options, callback);
   }
   createCryptoKey(
@@ -694,6 +728,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createCryptoKey(request, options, callback);
   }
   createCryptoKeyVersion(
@@ -760,6 +795,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createCryptoKeyVersion(request, options, callback);
   }
   importCryptoKeyVersion(
@@ -851,6 +887,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.importCryptoKeyVersion(request, options, callback);
   }
   createImportJob(
@@ -918,6 +955,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createImportJob(request, options, callback);
   }
   updateCryptoKey(
@@ -979,6 +1017,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'crypto_key.name': request.cryptoKey!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateCryptoKey(request, options, callback);
   }
   updateCryptoKeyVersion(
@@ -1046,6 +1085,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'crypto_key_version.name': request.cryptoKeyVersion!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateCryptoKeyVersion(request, options, callback);
   }
   encrypt(
@@ -1130,6 +1170,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.encrypt(request, options, callback);
   }
   decrypt(
@@ -1197,6 +1238,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.decrypt(request, options, callback);
   }
   asymmetricSign(
@@ -1262,6 +1304,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.asymmetricSign(request, options, callback);
   }
   asymmetricDecrypt(
@@ -1327,6 +1370,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.asymmetricDecrypt(request, options, callback);
   }
   updateCryptoKeyPrimaryVersion(
@@ -1390,6 +1434,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateCryptoKeyPrimaryVersion(request, options, callback);
   }
   destroyCryptoKeyVersion(
@@ -1460,6 +1505,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.destroyCryptoKeyVersion(request, options, callback);
   }
   restoreCryptoKeyVersion(
@@ -1525,6 +1571,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.restoreCryptoKeyVersion(request, options, callback);
   }
 
@@ -1614,6 +1661,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listKeyRings(request, options, callback);
   }
 
@@ -1667,6 +1715,7 @@ export class KeyManagementServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listKeyRings.createStream(
       this._innerApiCalls.listKeyRings as gax.GaxCall,
       request,
@@ -1761,6 +1810,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listCryptoKeys(request, options, callback);
   }
 
@@ -1816,6 +1866,7 @@ export class KeyManagementServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listCryptoKeys.createStream(
       this._innerApiCalls.listCryptoKeys as gax.GaxCall,
       request,
@@ -1911,6 +1962,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listCryptoKeyVersions(request, options, callback);
   }
 
@@ -1967,6 +2019,7 @@ export class KeyManagementServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listCryptoKeyVersions.createStream(
       this._innerApiCalls.listCryptoKeyVersions as gax.GaxCall,
       request,
@@ -2059,6 +2112,7 @@ export class KeyManagementServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listImportJobs(request, options, callback);
   }
 
@@ -2112,6 +2166,7 @@ export class KeyManagementServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listImportJobs.createStream(
       this._innerApiCalls.listImportJobs as gax.GaxCall,
       request,
@@ -2125,8 +2180,9 @@ export class KeyManagementServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.keyManagementServiceStub.then(stub => {
+      return this.keyManagementServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/kms/test/gapic-key_management_service-v1.ts.baseline b/baselines/kms/test/gapic-key_management_service-v1.ts.baseline
index b15bde0a6..ad4b25ba4 100644
--- a/baselines/kms/test/gapic-key_management_service-v1.ts.baseline
+++ b/baselines/kms/test/gapic-key_management_service-v1.ts.baseline
@@ -78,12 +78,30 @@ describe('v1.KeyManagementServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new keymanagementserviceModule.v1.KeyManagementServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.keyManagementServiceStub, undefined);
+        await client.initialize();
+        assert(client.keyManagementServiceStub);
+    });
+    it('has close method', () => {
+        const client = new keymanagementserviceModule.v1.KeyManagementServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getKeyRing', () => {
         it('invokes getKeyRing without error', done => {
             const client = new keymanagementserviceModule.v1.KeyManagementServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetKeyRingRequest = {};
             request.name = '';
@@ -107,6 +125,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetKeyRingRequest = {};
             request.name = '';
@@ -132,6 +152,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetCryptoKeyRequest = {};
             request.name = '';
@@ -155,6 +177,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetCryptoKeyRequest = {};
             request.name = '';
@@ -180,6 +204,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetCryptoKeyVersionRequest = {};
             request.name = '';
@@ -203,6 +229,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetCryptoKeyVersionRequest = {};
             request.name = '';
@@ -228,6 +256,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetPublicKeyRequest = {};
             request.name = '';
@@ -251,6 +281,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetPublicKeyRequest = {};
             request.name = '';
@@ -276,6 +308,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetImportJobRequest = {};
             request.name = '';
@@ -299,6 +333,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IGetImportJobRequest = {};
             request.name = '';
@@ -324,6 +360,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateKeyRingRequest = {};
             request.parent = '';
@@ -347,6 +385,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateKeyRingRequest = {};
             request.parent = '';
@@ -372,6 +412,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateCryptoKeyRequest = {};
             request.parent = '';
@@ -395,6 +437,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateCryptoKeyRequest = {};
             request.parent = '';
@@ -420,6 +464,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateCryptoKeyVersionRequest = {};
             request.parent = '';
@@ -443,6 +489,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateCryptoKeyVersionRequest = {};
             request.parent = '';
@@ -468,6 +516,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IImportCryptoKeyVersionRequest = {};
             request.parent = '';
@@ -491,6 +541,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IImportCryptoKeyVersionRequest = {};
             request.parent = '';
@@ -516,6 +568,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateImportJobRequest = {};
             request.parent = '';
@@ -539,6 +593,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.ICreateImportJobRequest = {};
             request.parent = '';
@@ -564,6 +620,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IUpdateCryptoKeyRequest = {};
             request.cryptoKey = {};
@@ -588,6 +646,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IUpdateCryptoKeyRequest = {};
             request.cryptoKey = {};
@@ -614,6 +674,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IUpdateCryptoKeyVersionRequest = {};
             request.cryptoKeyVersion = {};
@@ -638,6 +700,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IUpdateCryptoKeyVersionRequest = {};
             request.cryptoKeyVersion = {};
@@ -664,6 +728,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IEncryptRequest = {};
             request.name = '';
@@ -687,6 +753,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IEncryptRequest = {};
             request.name = '';
@@ -712,6 +780,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IDecryptRequest = {};
             request.name = '';
@@ -735,6 +805,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IDecryptRequest = {};
             request.name = '';
@@ -760,6 +832,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IAsymmetricSignRequest = {};
             request.name = '';
@@ -783,6 +857,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IAsymmetricSignRequest = {};
             request.name = '';
@@ -808,6 +884,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IAsymmetricDecryptRequest = {};
             request.name = '';
@@ -831,6 +909,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IAsymmetricDecryptRequest = {};
             request.name = '';
@@ -856,6 +936,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IUpdateCryptoKeyPrimaryVersionRequest = {};
             request.name = '';
@@ -879,6 +961,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IUpdateCryptoKeyPrimaryVersionRequest = {};
             request.name = '';
@@ -904,6 +988,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IDestroyCryptoKeyVersionRequest = {};
             request.name = '';
@@ -927,6 +1013,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IDestroyCryptoKeyVersionRequest = {};
             request.name = '';
@@ -952,6 +1040,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IRestoreCryptoKeyVersionRequest = {};
             request.name = '';
@@ -975,6 +1065,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IRestoreCryptoKeyVersionRequest = {};
             request.name = '';
@@ -1000,6 +1092,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListKeyRingsRequest = {};
             request.parent = '';
@@ -1023,6 +1117,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListKeyRingsRequest = {};
             request.parent = '';
@@ -1048,6 +1144,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListCryptoKeysRequest = {};
             request.parent = '';
@@ -1071,6 +1169,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListCryptoKeysRequest = {};
             request.parent = '';
@@ -1096,6 +1196,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListCryptoKeyVersionsRequest = {};
             request.parent = '';
@@ -1119,6 +1221,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListCryptoKeyVersionsRequest = {};
             request.parent = '';
@@ -1144,6 +1248,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListImportJobsRequest = {};
             request.parent = '';
@@ -1167,6 +1273,8 @@ describe('v1.KeyManagementServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.kms.v1.IListImportJobsRequest = {};
             request.parent = '';
diff --git a/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline b/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline
index 3a220fd38..c69322823 100644
--- a/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/alert_policy_service_client.ts.baseline
@@ -44,8 +44,13 @@ export class AlertPolicyServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  alertPolicyServiceStub: Promise<{[name: string]: Function}>;
+  alertPolicyServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of AlertPolicyServiceClient.
@@ -98,28 +103,31 @@ export class AlertPolicyServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof AlertPolicyServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -129,7 +137,7 @@ export class AlertPolicyServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -139,76 +147,76 @@ export class AlertPolicyServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      folderAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}'
       ),
-      folderAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      folderChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      folderGroupPathTemplate: new gaxModule.PathTemplate(
+      folderGroupPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/groups/{group}'
       ),
-      folderNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      folderNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannels/{notification_channel}'
       ),
-      folderServicePathTemplate: new gaxModule.PathTemplate(
+      folderServicePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}'
       ),
-      folderServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      folderServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      folderUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      folderUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      organizationAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}'
       ),
-      organizationAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      organizationChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      organizationGroupPathTemplate: new gaxModule.PathTemplate(
+      organizationGroupPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/groups/{group}'
       ),
-      organizationNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      organizationNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannels/{notification_channel}'
       ),
-      organizationServicePathTemplate: new gaxModule.PathTemplate(
+      organizationServicePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}'
       ),
-      organizationServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      organizationServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      organizationUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      organizationUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      projectAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}'
       ),
-      projectAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      projectChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      projectGroupPathTemplate: new gaxModule.PathTemplate(
+      projectGroupPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/groups/{group}'
       ),
-      projectNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      projectNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannels/{notification_channel}'
       ),
-      projectServicePathTemplate: new gaxModule.PathTemplate(
+      projectServicePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}'
       ),
-      projectServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      projectServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      projectUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      projectUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/uptimeCheckConfigs/{uptime_check_config}'
       ),
     };
@@ -218,11 +226,11 @@ export class AlertPolicyServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listAlertPolicies:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'alertPolicies')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'alertPolicies')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.monitoring.v3.AlertPolicyService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -230,15 +238,33 @@ export class AlertPolicyServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.alertPolicyServiceStub) {
+      return this.alertPolicyServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.monitoring.v3.AlertPolicyService.
-    this.alertPolicyServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.monitoring.v3.AlertPolicyService') :
+    this.alertPolicyServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.monitoring.v3.AlertPolicyService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.monitoring.v3.AlertPolicyService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.monitoring.v3.AlertPolicyService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -257,9 +283,9 @@ export class AlertPolicyServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -273,6 +299,8 @@ export class AlertPolicyServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.alertPolicyServiceStub;
   }
 
   /**
@@ -387,6 +415,7 @@ export class AlertPolicyServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getAlertPolicy(request, options, callback);
   }
   createAlertPolicy(
@@ -457,6 +486,7 @@ export class AlertPolicyServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.createAlertPolicy(request, options, callback);
   }
   deleteAlertPolicy(
@@ -520,6 +550,7 @@ export class AlertPolicyServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteAlertPolicy(request, options, callback);
   }
   updateAlertPolicy(
@@ -607,6 +638,7 @@ export class AlertPolicyServiceClient {
     ] = gax.routingHeader.fromParams({
       'alert_policy.name': request.alertPolicy!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateAlertPolicy(request, options, callback);
   }
 
@@ -709,6 +741,7 @@ export class AlertPolicyServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listAlertPolicies(request, options, callback);
   }
 
@@ -775,6 +808,7 @@ export class AlertPolicyServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listAlertPolicies.createStream(
       this._innerApiCalls.listAlertPolicies as gax.GaxCall,
       request,
@@ -1733,8 +1767,9 @@ export class AlertPolicyServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.alertPolicyServiceStub.then(stub => {
+      return this.alertPolicyServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/monitoring/src/v3/group_service_client.ts.baseline b/baselines/monitoring/src/v3/group_service_client.ts.baseline
index dd057c86e..03eceac6a 100644
--- a/baselines/monitoring/src/v3/group_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/group_service_client.ts.baseline
@@ -47,8 +47,13 @@ export class GroupServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  groupServiceStub: Promise<{[name: string]: Function}>;
+  groupServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of GroupServiceClient.
@@ -101,28 +106,31 @@ export class GroupServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof GroupServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -132,7 +140,7 @@ export class GroupServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -142,76 +150,76 @@ export class GroupServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      folderAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}'
       ),
-      folderAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      folderChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      folderGroupPathTemplate: new gaxModule.PathTemplate(
+      folderGroupPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/groups/{group}'
       ),
-      folderNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      folderNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannels/{notification_channel}'
       ),
-      folderServicePathTemplate: new gaxModule.PathTemplate(
+      folderServicePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}'
       ),
-      folderServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      folderServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      folderUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      folderUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      organizationAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}'
       ),
-      organizationAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      organizationChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      organizationGroupPathTemplate: new gaxModule.PathTemplate(
+      organizationGroupPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/groups/{group}'
       ),
-      organizationNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      organizationNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannels/{notification_channel}'
       ),
-      organizationServicePathTemplate: new gaxModule.PathTemplate(
+      organizationServicePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}'
       ),
-      organizationServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      organizationServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      organizationUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      organizationUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      projectAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}'
       ),
-      projectAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      projectChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      projectGroupPathTemplate: new gaxModule.PathTemplate(
+      projectGroupPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/groups/{group}'
       ),
-      projectNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      projectNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannels/{notification_channel}'
       ),
-      projectServicePathTemplate: new gaxModule.PathTemplate(
+      projectServicePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}'
       ),
-      projectServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      projectServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      projectUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      projectUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/uptimeCheckConfigs/{uptime_check_config}'
       ),
     };
@@ -221,13 +229,13 @@ export class GroupServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listGroups:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'group'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'group'),
       listGroupMembers:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'members')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'members')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.monitoring.v3.GroupService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -235,15 +243,33 @@ export class GroupServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.groupServiceStub) {
+      return this.groupServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.monitoring.v3.GroupService.
-    this.groupServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.monitoring.v3.GroupService') :
+    this.groupServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.monitoring.v3.GroupService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.monitoring.v3.GroupService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.monitoring.v3.GroupService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -262,9 +288,9 @@ export class GroupServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -278,6 +304,8 @@ export class GroupServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.groupServiceStub;
   }
 
   /**
@@ -391,6 +419,7 @@ export class GroupServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getGroup(request, options, callback);
   }
   createGroup(
@@ -456,6 +485,7 @@ export class GroupServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.createGroup(request, options, callback);
   }
   updateGroup(
@@ -519,6 +549,7 @@ export class GroupServiceClient {
     ] = gax.routingHeader.fromParams({
       'group.name': request.group!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateGroup(request, options, callback);
   }
   deleteGroup(
@@ -583,6 +614,7 @@ export class GroupServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteGroup(request, options, callback);
   }
 
@@ -680,6 +712,7 @@ export class GroupServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listGroups(request, options, callback);
   }
 
@@ -741,6 +774,7 @@ export class GroupServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listGroups.createStream(
       this._innerApiCalls.listGroups as gax.GaxCall,
       request,
@@ -839,6 +873,7 @@ export class GroupServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listGroupMembers(request, options, callback);
   }
 
@@ -898,6 +933,7 @@ export class GroupServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listGroupMembers.createStream(
       this._innerApiCalls.listGroupMembers as gax.GaxCall,
       request,
@@ -1856,8 +1892,9 @@ export class GroupServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.groupServiceStub.then(stub => {
+      return this.groupServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/monitoring/src/v3/metric_service_client.ts.baseline b/baselines/monitoring/src/v3/metric_service_client.ts.baseline
index 15bf8586a..2bf394d26 100644
--- a/baselines/monitoring/src/v3/metric_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/metric_service_client.ts.baseline
@@ -37,8 +37,13 @@ export class MetricServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  metricServiceStub: Promise<{[name: string]: Function}>;
+  metricServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of MetricServiceClient.
@@ -91,28 +96,31 @@ export class MetricServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof MetricServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -122,7 +130,7 @@ export class MetricServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -132,94 +140,94 @@ export class MetricServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      folderAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}'
       ),
-      folderAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      folderChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      folderGroupPathTemplate: new gaxModule.PathTemplate(
+      folderGroupPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/groups/{group}'
       ),
-      folderMetricDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderMetricDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/metricDescriptors/{metric_descriptor=**}'
       ),
-      folderMonitoredResourceDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderMonitoredResourceDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/monitoredResourceDescriptors/{monitored_resource_descriptor}'
       ),
-      folderNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      folderNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannels/{notification_channel}'
       ),
-      folderServicePathTemplate: new gaxModule.PathTemplate(
+      folderServicePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}'
       ),
-      folderServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      folderServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      folderUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      folderUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      organizationAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}'
       ),
-      organizationAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      organizationChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      organizationGroupPathTemplate: new gaxModule.PathTemplate(
+      organizationGroupPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/groups/{group}'
       ),
-      organizationMetricDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationMetricDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/metricDescriptors/{metric_descriptor=**}'
       ),
-      organizationMonitoredResourceDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationMonitoredResourceDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/monitoredResourceDescriptors/{monitored_resource_descriptor}'
       ),
-      organizationNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      organizationNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannels/{notification_channel}'
       ),
-      organizationServicePathTemplate: new gaxModule.PathTemplate(
+      organizationServicePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}'
       ),
-      organizationServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      organizationServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      organizationUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      organizationUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      projectAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}'
       ),
-      projectAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      projectChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      projectGroupPathTemplate: new gaxModule.PathTemplate(
+      projectGroupPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/groups/{group}'
       ),
-      projectMetricDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectMetricDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/metricDescriptors/{metric_descriptor=**}'
       ),
-      projectMonitoredResourceDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectMonitoredResourceDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/monitoredResourceDescriptors/{monitored_resource_descriptor}'
       ),
-      projectNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      projectNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannels/{notification_channel}'
       ),
-      projectServicePathTemplate: new gaxModule.PathTemplate(
+      projectServicePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}'
       ),
-      projectServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      projectServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      projectUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      projectUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/uptimeCheckConfigs/{uptime_check_config}'
       ),
     };
@@ -229,15 +237,15 @@ export class MetricServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listMonitoredResourceDescriptors:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'resourceDescriptors'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'resourceDescriptors'),
       listMetricDescriptors:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'metricDescriptors'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'metricDescriptors'),
       listTimeSeries:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'timeSeries')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'timeSeries')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.monitoring.v3.MetricService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -245,15 +253,33 @@ export class MetricServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.metricServiceStub) {
+      return this.metricServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.monitoring.v3.MetricService.
-    this.metricServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.monitoring.v3.MetricService') :
+    this.metricServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.monitoring.v3.MetricService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.monitoring.v3.MetricService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.monitoring.v3.MetricService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -272,9 +298,9 @@ export class MetricServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -288,6 +314,8 @@ export class MetricServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.metricServiceStub;
   }
 
   /**
@@ -404,6 +432,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getMonitoredResourceDescriptor(request, options, callback);
   }
   getMetricDescriptor(
@@ -466,6 +495,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getMetricDescriptor(request, options, callback);
   }
   createMetricDescriptor(
@@ -531,6 +561,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.createMetricDescriptor(request, options, callback);
   }
   deleteMetricDescriptor(
@@ -594,6 +625,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteMetricDescriptor(request, options, callback);
   }
   createTimeSeries(
@@ -665,6 +697,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.createTimeSeries(request, options, callback);
   }
 
@@ -755,6 +788,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listMonitoredResourceDescriptors(request, options, callback);
   }
 
@@ -809,6 +843,7 @@ export class MetricServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listMonitoredResourceDescriptors.createStream(
       this._innerApiCalls.listMonitoredResourceDescriptors as gax.GaxCall,
       request,
@@ -903,6 +938,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listMetricDescriptors(request, options, callback);
   }
 
@@ -958,6 +994,7 @@ export class MetricServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listMetricDescriptors.createStream(
       this._innerApiCalls.listMetricDescriptors as gax.GaxCall,
       request,
@@ -1070,6 +1107,7 @@ export class MetricServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listTimeSeries(request, options, callback);
   }
 
@@ -1143,6 +1181,7 @@ export class MetricServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listTimeSeries.createStream(
       this._innerApiCalls.listTimeSeries as gax.GaxCall,
       request,
@@ -2317,8 +2356,9 @@ export class MetricServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.metricServiceStub.then(stub => {
+      return this.metricServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline b/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline
index 6cbd0a859..fd20fd543 100644
--- a/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/notification_channel_service_client.ts.baseline
@@ -37,8 +37,13 @@ export class NotificationChannelServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  notificationChannelServiceStub: Promise<{[name: string]: Function}>;
+  notificationChannelServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of NotificationChannelServiceClient.
@@ -91,28 +96,31 @@ export class NotificationChannelServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof NotificationChannelServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -122,7 +130,7 @@ export class NotificationChannelServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -132,76 +140,76 @@ export class NotificationChannelServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      folderAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}'
       ),
-      folderAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      folderChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      folderGroupPathTemplate: new gaxModule.PathTemplate(
+      folderGroupPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/groups/{group}'
       ),
-      folderNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      folderNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannels/{notification_channel}'
       ),
-      folderServicePathTemplate: new gaxModule.PathTemplate(
+      folderServicePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}'
       ),
-      folderServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      folderServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      folderUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      folderUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      organizationAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}'
       ),
-      organizationAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      organizationChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      organizationGroupPathTemplate: new gaxModule.PathTemplate(
+      organizationGroupPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/groups/{group}'
       ),
-      organizationNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      organizationNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannels/{notification_channel}'
       ),
-      organizationServicePathTemplate: new gaxModule.PathTemplate(
+      organizationServicePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}'
       ),
-      organizationServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      organizationServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      organizationUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      organizationUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      projectAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}'
       ),
-      projectAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      projectChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      projectGroupPathTemplate: new gaxModule.PathTemplate(
+      projectGroupPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/groups/{group}'
       ),
-      projectNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      projectNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannels/{notification_channel}'
       ),
-      projectServicePathTemplate: new gaxModule.PathTemplate(
+      projectServicePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}'
       ),
-      projectServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      projectServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      projectUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      projectUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/uptimeCheckConfigs/{uptime_check_config}'
       ),
     };
@@ -211,13 +219,13 @@ export class NotificationChannelServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listNotificationChannelDescriptors:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'channelDescriptors'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'channelDescriptors'),
       listNotificationChannels:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'notificationChannels')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'notificationChannels')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.monitoring.v3.NotificationChannelService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -225,15 +233,33 @@ export class NotificationChannelServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.notificationChannelServiceStub) {
+      return this.notificationChannelServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.monitoring.v3.NotificationChannelService.
-    this.notificationChannelServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.monitoring.v3.NotificationChannelService') :
+    this.notificationChannelServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.monitoring.v3.NotificationChannelService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.monitoring.v3.NotificationChannelService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.monitoring.v3.NotificationChannelService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -252,9 +278,9 @@ export class NotificationChannelServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -268,6 +294,8 @@ export class NotificationChannelServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.notificationChannelServiceStub;
   }
 
   /**
@@ -382,6 +410,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getNotificationChannelDescriptor(request, options, callback);
   }
   getNotificationChannel(
@@ -446,6 +475,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getNotificationChannel(request, options, callback);
   }
   createNotificationChannel(
@@ -515,6 +545,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.createNotificationChannel(request, options, callback);
   }
   updateNotificationChannel(
@@ -580,6 +611,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'notification_channel.name': request.notificationChannel!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateNotificationChannel(request, options, callback);
   }
   deleteNotificationChannel(
@@ -645,6 +677,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteNotificationChannel(request, options, callback);
   }
   sendNotificationChannelVerificationCode(
@@ -705,6 +738,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.sendNotificationChannelVerificationCode(request, options, callback);
   }
   getNotificationChannelVerificationCode(
@@ -796,6 +830,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getNotificationChannelVerificationCode(request, options, callback);
   }
   verifyNotificationChannel(
@@ -865,6 +900,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.verifyNotificationChannel(request, options, callback);
   }
 
@@ -957,6 +993,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listNotificationChannelDescriptors(request, options, callback);
   }
 
@@ -1012,6 +1049,7 @@ export class NotificationChannelServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listNotificationChannelDescriptors.createStream(
       this._innerApiCalls.listNotificationChannelDescriptors as gax.GaxCall,
       request,
@@ -1117,6 +1155,7 @@ export class NotificationChannelServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.listNotificationChannels(request, options, callback);
   }
 
@@ -1183,6 +1222,7 @@ export class NotificationChannelServiceClient {
       'name': request.name || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listNotificationChannels.createStream(
       this._innerApiCalls.listNotificationChannels as gax.GaxCall,
       request,
@@ -2141,8 +2181,9 @@ export class NotificationChannelServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.notificationChannelServiceStub.then(stub => {
+      return this.notificationChannelServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline b/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline
index b0f487f74..3212c34b0 100644
--- a/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/service_monitoring_service_client.ts.baseline
@@ -39,8 +39,13 @@ export class ServiceMonitoringServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  serviceMonitoringServiceStub: Promise<{[name: string]: Function}>;
+  serviceMonitoringServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of ServiceMonitoringServiceClient.
@@ -93,28 +98,31 @@ export class ServiceMonitoringServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof ServiceMonitoringServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -124,7 +132,7 @@ export class ServiceMonitoringServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -134,76 +142,76 @@ export class ServiceMonitoringServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      folderAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}'
       ),
-      folderAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      folderChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      folderGroupPathTemplate: new gaxModule.PathTemplate(
+      folderGroupPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/groups/{group}'
       ),
-      folderNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      folderNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannels/{notification_channel}'
       ),
-      folderServicePathTemplate: new gaxModule.PathTemplate(
+      folderServicePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}'
       ),
-      folderServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      folderServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      folderUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      folderUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      organizationAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}'
       ),
-      organizationAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      organizationChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      organizationGroupPathTemplate: new gaxModule.PathTemplate(
+      organizationGroupPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/groups/{group}'
       ),
-      organizationNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      organizationNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannels/{notification_channel}'
       ),
-      organizationServicePathTemplate: new gaxModule.PathTemplate(
+      organizationServicePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}'
       ),
-      organizationServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      organizationServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      organizationUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      organizationUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      projectAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}'
       ),
-      projectAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      projectChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      projectGroupPathTemplate: new gaxModule.PathTemplate(
+      projectGroupPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/groups/{group}'
       ),
-      projectNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      projectNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannels/{notification_channel}'
       ),
-      projectServicePathTemplate: new gaxModule.PathTemplate(
+      projectServicePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}'
       ),
-      projectServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      projectServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      projectUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      projectUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/uptimeCheckConfigs/{uptime_check_config}'
       ),
     };
@@ -213,13 +221,13 @@ export class ServiceMonitoringServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listServices:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'services'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'services'),
       listServiceLevelObjectives:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'serviceLevelObjectives')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'serviceLevelObjectives')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.monitoring.v3.ServiceMonitoringService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -227,15 +235,33 @@ export class ServiceMonitoringServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.serviceMonitoringServiceStub) {
+      return this.serviceMonitoringServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.monitoring.v3.ServiceMonitoringService.
-    this.serviceMonitoringServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.monitoring.v3.ServiceMonitoringService') :
+    this.serviceMonitoringServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.monitoring.v3.ServiceMonitoringService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.monitoring.v3.ServiceMonitoringService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.monitoring.v3.ServiceMonitoringService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -254,9 +280,9 @@ export class ServiceMonitoringServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -270,6 +296,8 @@ export class ServiceMonitoringServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.serviceMonitoringServiceStub;
   }
 
   /**
@@ -388,6 +416,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createService(request, options, callback);
   }
   getService(
@@ -448,6 +477,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getService(request, options, callback);
   }
   updateService(
@@ -510,6 +540,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'service.name': request.service!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateService(request, options, callback);
   }
   deleteService(
@@ -570,6 +601,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteService(request, options, callback);
   }
   createServiceLevelObjective(
@@ -638,6 +670,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createServiceLevelObjective(request, options, callback);
   }
   getServiceLevelObjective(
@@ -704,6 +737,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getServiceLevelObjective(request, options, callback);
   }
   updateServiceLevelObjective(
@@ -766,6 +800,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'service_level_objective.name': request.serviceLevelObjective!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateServiceLevelObjective(request, options, callback);
   }
   deleteServiceLevelObjective(
@@ -827,6 +862,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteServiceLevelObjective(request, options, callback);
   }
 
@@ -926,6 +962,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listServices(request, options, callback);
   }
 
@@ -989,6 +1026,7 @@ export class ServiceMonitoringServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listServices.createStream(
       this._innerApiCalls.listServices as gax.GaxCall,
       request,
@@ -1082,6 +1120,7 @@ export class ServiceMonitoringServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listServiceLevelObjectives(request, options, callback);
   }
 
@@ -1136,6 +1175,7 @@ export class ServiceMonitoringServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listServiceLevelObjectives.createStream(
       this._innerApiCalls.listServiceLevelObjectives as gax.GaxCall,
       request,
@@ -2094,8 +2134,9 @@ export class ServiceMonitoringServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.serviceMonitoringServiceStub.then(stub => {
+      return this.serviceMonitoringServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline b/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline
index 2e5537f54..c97f00585 100644
--- a/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline
+++ b/baselines/monitoring/src/v3/uptime_check_service_client.ts.baseline
@@ -43,8 +43,13 @@ export class UptimeCheckServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  uptimeCheckServiceStub: Promise<{[name: string]: Function}>;
+  uptimeCheckServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of UptimeCheckServiceClient.
@@ -97,28 +102,31 @@ export class UptimeCheckServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof UptimeCheckServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -128,7 +136,7 @@ export class UptimeCheckServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -138,76 +146,76 @@ export class UptimeCheckServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      folderAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}'
       ),
-      folderAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      folderAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      folderChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      folderChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      folderGroupPathTemplate: new gaxModule.PathTemplate(
+      folderGroupPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/groups/{group}'
       ),
-      folderNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      folderNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/notificationChannels/{notification_channel}'
       ),
-      folderServicePathTemplate: new gaxModule.PathTemplate(
+      folderServicePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}'
       ),
-      folderServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      folderServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      folderUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      folderUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'folders/{folder}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      organizationAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}'
       ),
-      organizationAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      organizationAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      organizationChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      organizationChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      organizationGroupPathTemplate: new gaxModule.PathTemplate(
+      organizationGroupPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/groups/{group}'
       ),
-      organizationNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      organizationNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/notificationChannels/{notification_channel}'
       ),
-      organizationServicePathTemplate: new gaxModule.PathTemplate(
+      organizationServicePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}'
       ),
-      organizationServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      organizationServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      organizationUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      organizationUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'organizations/{organization}/uptimeCheckConfigs/{uptime_check_config}'
       ),
-      projectAlertPolicyPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}'
       ),
-      projectAlertPolicyConditionPathTemplate: new gaxModule.PathTemplate(
+      projectAlertPolicyConditionPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/alertPolicies/{alert_policy}/conditions/{condition}'
       ),
-      projectChannelDescriptorPathTemplate: new gaxModule.PathTemplate(
+      projectChannelDescriptorPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannelDescriptors/{channel_descriptor}'
       ),
-      projectGroupPathTemplate: new gaxModule.PathTemplate(
+      projectGroupPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/groups/{group}'
       ),
-      projectNotificationChannelPathTemplate: new gaxModule.PathTemplate(
+      projectNotificationChannelPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/notificationChannels/{notification_channel}'
       ),
-      projectServicePathTemplate: new gaxModule.PathTemplate(
+      projectServicePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}'
       ),
-      projectServiceServiceLevelObjectivePathTemplate: new gaxModule.PathTemplate(
+      projectServiceServiceLevelObjectivePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/services/{service}/serviceLevelObjectives/{service_level_objective}'
       ),
-      projectUptimeCheckConfigPathTemplate: new gaxModule.PathTemplate(
+      projectUptimeCheckConfigPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/uptimeCheckConfigs/{uptime_check_config}'
       ),
     };
@@ -217,13 +225,13 @@ export class UptimeCheckServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listUptimeCheckConfigs:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'uptimeCheckConfigs'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'uptimeCheckConfigs'),
       listUptimeCheckIps:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'uptimeCheckIps')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'uptimeCheckIps')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.monitoring.v3.UptimeCheckService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -231,15 +239,33 @@ export class UptimeCheckServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.uptimeCheckServiceStub) {
+      return this.uptimeCheckServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.monitoring.v3.UptimeCheckService.
-    this.uptimeCheckServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.monitoring.v3.UptimeCheckService') :
+    this.uptimeCheckServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.monitoring.v3.UptimeCheckService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.monitoring.v3.UptimeCheckService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.monitoring.v3.UptimeCheckService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -258,9 +284,9 @@ export class UptimeCheckServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -274,6 +300,8 @@ export class UptimeCheckServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.uptimeCheckServiceStub;
   }
 
   /**
@@ -387,6 +415,7 @@ export class UptimeCheckServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getUptimeCheckConfig(request, options, callback);
   }
   createUptimeCheckConfig(
@@ -449,6 +478,7 @@ export class UptimeCheckServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createUptimeCheckConfig(request, options, callback);
   }
   updateUptimeCheckConfig(
@@ -526,6 +556,7 @@ export class UptimeCheckServiceClient {
     ] = gax.routingHeader.fromParams({
       'uptime_check_config.name': request.uptimeCheckConfig!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateUptimeCheckConfig(request, options, callback);
   }
   deleteUptimeCheckConfig(
@@ -588,6 +619,7 @@ export class UptimeCheckServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteUptimeCheckConfig(request, options, callback);
   }
 
@@ -674,6 +706,7 @@ export class UptimeCheckServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listUptimeCheckConfigs(request, options, callback);
   }
 
@@ -723,6 +756,7 @@ export class UptimeCheckServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listUptimeCheckConfigs.createStream(
       this._innerApiCalls.listUptimeCheckConfigs as gax.GaxCall,
       request,
@@ -803,6 +837,7 @@ export class UptimeCheckServiceClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.listUptimeCheckIps(request, options, callback);
   }
 
@@ -844,6 +879,7 @@ export class UptimeCheckServiceClient {
     request = request || {};
     options = options || {};
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listUptimeCheckIps.createStream(
       this._innerApiCalls.listUptimeCheckIps as gax.GaxCall,
       request,
@@ -1802,8 +1838,9 @@ export class UptimeCheckServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.uptimeCheckServiceStub.then(stub => {
+      return this.uptimeCheckServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/monitoring/test/gapic-alert_policy_service-v3.ts.baseline b/baselines/monitoring/test/gapic-alert_policy_service-v3.ts.baseline
index 13fa999b8..d819d6c13 100644
--- a/baselines/monitoring/test/gapic-alert_policy_service-v3.ts.baseline
+++ b/baselines/monitoring/test/gapic-alert_policy_service-v3.ts.baseline
@@ -78,12 +78,30 @@ describe('v3.AlertPolicyServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new alertpolicyserviceModule.v3.AlertPolicyServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.alertPolicyServiceStub, undefined);
+        await client.initialize();
+        assert(client.alertPolicyServiceStub);
+    });
+    it('has close method', () => {
+        const client = new alertpolicyserviceModule.v3.AlertPolicyServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getAlertPolicy', () => {
         it('invokes getAlertPolicy without error', done => {
             const client = new alertpolicyserviceModule.v3.AlertPolicyServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetAlertPolicyRequest = {};
             request.name = '';
@@ -107,6 +125,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetAlertPolicyRequest = {};
             request.name = '';
@@ -132,6 +152,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateAlertPolicyRequest = {};
             request.name = '';
@@ -155,6 +177,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateAlertPolicyRequest = {};
             request.name = '';
@@ -180,6 +204,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteAlertPolicyRequest = {};
             request.name = '';
@@ -203,6 +229,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteAlertPolicyRequest = {};
             request.name = '';
@@ -228,6 +256,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateAlertPolicyRequest = {};
             request.alertPolicy = {};
@@ -252,6 +282,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateAlertPolicyRequest = {};
             request.alertPolicy = {};
@@ -278,6 +310,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListAlertPoliciesRequest = {};
             request.name = '';
@@ -301,6 +335,8 @@ describe('v3.AlertPolicyServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListAlertPoliciesRequest = {};
             request.name = '';
diff --git a/baselines/monitoring/test/gapic-group_service-v3.ts.baseline b/baselines/monitoring/test/gapic-group_service-v3.ts.baseline
index df8dfb910..5ce2c4377 100644
--- a/baselines/monitoring/test/gapic-group_service-v3.ts.baseline
+++ b/baselines/monitoring/test/gapic-group_service-v3.ts.baseline
@@ -78,12 +78,30 @@ describe('v3.GroupServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new groupserviceModule.v3.GroupServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.groupServiceStub, undefined);
+        await client.initialize();
+        assert(client.groupServiceStub);
+    });
+    it('has close method', () => {
+        const client = new groupserviceModule.v3.GroupServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getGroup', () => {
         it('invokes getGroup without error', done => {
             const client = new groupserviceModule.v3.GroupServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetGroupRequest = {};
             request.name = '';
@@ -107,6 +125,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetGroupRequest = {};
             request.name = '';
@@ -132,6 +152,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateGroupRequest = {};
             request.name = '';
@@ -155,6 +177,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateGroupRequest = {};
             request.name = '';
@@ -180,6 +204,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateGroupRequest = {};
             request.group = {};
@@ -204,6 +230,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateGroupRequest = {};
             request.group = {};
@@ -230,6 +258,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteGroupRequest = {};
             request.name = '';
@@ -253,6 +283,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteGroupRequest = {};
             request.name = '';
@@ -278,6 +310,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListGroupsRequest = {};
             request.name = '';
@@ -301,6 +335,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListGroupsRequest = {};
             request.name = '';
@@ -326,6 +362,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListGroupMembersRequest = {};
             request.name = '';
@@ -349,6 +387,8 @@ describe('v3.GroupServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListGroupMembersRequest = {};
             request.name = '';
diff --git a/baselines/monitoring/test/gapic-metric_service-v3.ts.baseline b/baselines/monitoring/test/gapic-metric_service-v3.ts.baseline
index a709a3212..3ad923e29 100644
--- a/baselines/monitoring/test/gapic-metric_service-v3.ts.baseline
+++ b/baselines/monitoring/test/gapic-metric_service-v3.ts.baseline
@@ -78,12 +78,30 @@ describe('v3.MetricServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new metricserviceModule.v3.MetricServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.metricServiceStub, undefined);
+        await client.initialize();
+        assert(client.metricServiceStub);
+    });
+    it('has close method', () => {
+        const client = new metricserviceModule.v3.MetricServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getMonitoredResourceDescriptor', () => {
         it('invokes getMonitoredResourceDescriptor without error', done => {
             const client = new metricserviceModule.v3.MetricServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetMonitoredResourceDescriptorRequest = {};
             request.name = '';
@@ -107,6 +125,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetMonitoredResourceDescriptorRequest = {};
             request.name = '';
@@ -132,6 +152,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetMetricDescriptorRequest = {};
             request.name = '';
@@ -155,6 +177,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetMetricDescriptorRequest = {};
             request.name = '';
@@ -180,6 +204,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateMetricDescriptorRequest = {};
             request.name = '';
@@ -203,6 +229,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateMetricDescriptorRequest = {};
             request.name = '';
@@ -228,6 +256,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteMetricDescriptorRequest = {};
             request.name = '';
@@ -251,6 +281,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteMetricDescriptorRequest = {};
             request.name = '';
@@ -276,6 +308,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateTimeSeriesRequest = {};
             request.name = '';
@@ -299,6 +333,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateTimeSeriesRequest = {};
             request.name = '';
@@ -324,6 +360,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListMonitoredResourceDescriptorsRequest = {};
             request.name = '';
@@ -347,6 +385,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListMonitoredResourceDescriptorsRequest = {};
             request.name = '';
@@ -372,6 +412,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListMetricDescriptorsRequest = {};
             request.name = '';
@@ -395,6 +437,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListMetricDescriptorsRequest = {};
             request.name = '';
@@ -420,6 +464,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListTimeSeriesRequest = {};
             request.name = '';
@@ -443,6 +489,8 @@ describe('v3.MetricServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListTimeSeriesRequest = {};
             request.name = '';
diff --git a/baselines/monitoring/test/gapic-notification_channel_service-v3.ts.baseline b/baselines/monitoring/test/gapic-notification_channel_service-v3.ts.baseline
index e3fff90fc..f5928fd7d 100644
--- a/baselines/monitoring/test/gapic-notification_channel_service-v3.ts.baseline
+++ b/baselines/monitoring/test/gapic-notification_channel_service-v3.ts.baseline
@@ -78,12 +78,30 @@ describe('v3.NotificationChannelServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new notificationchannelserviceModule.v3.NotificationChannelServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.notificationChannelServiceStub, undefined);
+        await client.initialize();
+        assert(client.notificationChannelServiceStub);
+    });
+    it('has close method', () => {
+        const client = new notificationchannelserviceModule.v3.NotificationChannelServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getNotificationChannelDescriptor', () => {
         it('invokes getNotificationChannelDescriptor without error', done => {
             const client = new notificationchannelserviceModule.v3.NotificationChannelServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetNotificationChannelDescriptorRequest = {};
             request.name = '';
@@ -107,6 +125,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetNotificationChannelDescriptorRequest = {};
             request.name = '';
@@ -132,6 +152,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetNotificationChannelRequest = {};
             request.name = '';
@@ -155,6 +177,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetNotificationChannelRequest = {};
             request.name = '';
@@ -180,6 +204,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateNotificationChannelRequest = {};
             request.name = '';
@@ -203,6 +229,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateNotificationChannelRequest = {};
             request.name = '';
@@ -228,6 +256,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateNotificationChannelRequest = {};
             request.notificationChannel = {};
@@ -252,6 +282,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateNotificationChannelRequest = {};
             request.notificationChannel = {};
@@ -278,6 +310,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteNotificationChannelRequest = {};
             request.name = '';
@@ -301,6 +335,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteNotificationChannelRequest = {};
             request.name = '';
@@ -326,6 +362,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ISendNotificationChannelVerificationCodeRequest = {};
             request.name = '';
@@ -349,6 +387,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ISendNotificationChannelVerificationCodeRequest = {};
             request.name = '';
@@ -374,6 +414,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetNotificationChannelVerificationCodeRequest = {};
             request.name = '';
@@ -397,6 +439,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetNotificationChannelVerificationCodeRequest = {};
             request.name = '';
@@ -422,6 +466,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IVerifyNotificationChannelRequest = {};
             request.name = '';
@@ -445,6 +491,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IVerifyNotificationChannelRequest = {};
             request.name = '';
@@ -470,6 +518,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListNotificationChannelDescriptorsRequest = {};
             request.name = '';
@@ -493,6 +543,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListNotificationChannelDescriptorsRequest = {};
             request.name = '';
@@ -518,6 +570,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListNotificationChannelsRequest = {};
             request.name = '';
@@ -541,6 +595,8 @@ describe('v3.NotificationChannelServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListNotificationChannelsRequest = {};
             request.name = '';
diff --git a/baselines/monitoring/test/gapic-service_monitoring_service-v3.ts.baseline b/baselines/monitoring/test/gapic-service_monitoring_service-v3.ts.baseline
index 780f79dd4..9392ce2d1 100644
--- a/baselines/monitoring/test/gapic-service_monitoring_service-v3.ts.baseline
+++ b/baselines/monitoring/test/gapic-service_monitoring_service-v3.ts.baseline
@@ -78,12 +78,30 @@ describe('v3.ServiceMonitoringServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new servicemonitoringserviceModule.v3.ServiceMonitoringServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.serviceMonitoringServiceStub, undefined);
+        await client.initialize();
+        assert(client.serviceMonitoringServiceStub);
+    });
+    it('has close method', () => {
+        const client = new servicemonitoringserviceModule.v3.ServiceMonitoringServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('createService', () => {
         it('invokes createService without error', done => {
             const client = new servicemonitoringserviceModule.v3.ServiceMonitoringServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateServiceRequest = {};
             request.parent = '';
@@ -107,6 +125,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateServiceRequest = {};
             request.parent = '';
@@ -132,6 +152,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetServiceRequest = {};
             request.name = '';
@@ -155,6 +177,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetServiceRequest = {};
             request.name = '';
@@ -180,6 +204,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateServiceRequest = {};
             request.service = {};
@@ -204,6 +230,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateServiceRequest = {};
             request.service = {};
@@ -230,6 +258,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteServiceRequest = {};
             request.name = '';
@@ -253,6 +283,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteServiceRequest = {};
             request.name = '';
@@ -278,6 +310,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateServiceLevelObjectiveRequest = {};
             request.parent = '';
@@ -301,6 +335,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateServiceLevelObjectiveRequest = {};
             request.parent = '';
@@ -326,6 +362,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetServiceLevelObjectiveRequest = {};
             request.name = '';
@@ -349,6 +387,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetServiceLevelObjectiveRequest = {};
             request.name = '';
@@ -374,6 +414,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateServiceLevelObjectiveRequest = {};
             request.serviceLevelObjective = {};
@@ -398,6 +440,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateServiceLevelObjectiveRequest = {};
             request.serviceLevelObjective = {};
@@ -424,6 +468,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteServiceLevelObjectiveRequest = {};
             request.name = '';
@@ -447,6 +493,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteServiceLevelObjectiveRequest = {};
             request.name = '';
@@ -472,6 +520,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListServicesRequest = {};
             request.parent = '';
@@ -495,6 +545,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListServicesRequest = {};
             request.parent = '';
@@ -520,6 +572,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListServiceLevelObjectivesRequest = {};
             request.parent = '';
@@ -543,6 +597,8 @@ describe('v3.ServiceMonitoringServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListServiceLevelObjectivesRequest = {};
             request.parent = '';
diff --git a/baselines/monitoring/test/gapic-uptime_check_service-v3.ts.baseline b/baselines/monitoring/test/gapic-uptime_check_service-v3.ts.baseline
index f7c232f70..21a9700c3 100644
--- a/baselines/monitoring/test/gapic-uptime_check_service-v3.ts.baseline
+++ b/baselines/monitoring/test/gapic-uptime_check_service-v3.ts.baseline
@@ -78,12 +78,30 @@ describe('v3.UptimeCheckServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new uptimecheckserviceModule.v3.UptimeCheckServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.uptimeCheckServiceStub, undefined);
+        await client.initialize();
+        assert(client.uptimeCheckServiceStub);
+    });
+    it('has close method', () => {
+        const client = new uptimecheckserviceModule.v3.UptimeCheckServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getUptimeCheckConfig', () => {
         it('invokes getUptimeCheckConfig without error', done => {
             const client = new uptimecheckserviceModule.v3.UptimeCheckServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetUptimeCheckConfigRequest = {};
             request.name = '';
@@ -107,6 +125,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IGetUptimeCheckConfigRequest = {};
             request.name = '';
@@ -132,6 +152,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateUptimeCheckConfigRequest = {};
             request.parent = '';
@@ -155,6 +177,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.ICreateUptimeCheckConfigRequest = {};
             request.parent = '';
@@ -180,6 +204,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateUptimeCheckConfigRequest = {};
             request.uptimeCheckConfig = {};
@@ -204,6 +230,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IUpdateUptimeCheckConfigRequest = {};
             request.uptimeCheckConfig = {};
@@ -230,6 +258,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteUptimeCheckConfigRequest = {};
             request.name = '';
@@ -253,6 +283,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IDeleteUptimeCheckConfigRequest = {};
             request.name = '';
@@ -278,6 +310,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListUptimeCheckConfigsRequest = {};
             request.parent = '';
@@ -301,6 +335,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListUptimeCheckConfigsRequest = {};
             request.parent = '';
@@ -326,6 +362,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListUptimeCheckIpsRequest = {};
             // Mock response
@@ -348,6 +386,8 @@ describe('v3.UptimeCheckServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.monitoring.v3.IListUptimeCheckIpsRequest = {};
             // Mock response
diff --git a/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline b/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline
index ababe81cf..953aba00a 100644
--- a/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline
+++ b/baselines/redis/src/v1beta1/cloud_redis_client.ts.baseline
@@ -50,9 +50,14 @@ export class CloudRedisClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
   operationsClient: gax.OperationsClient;
-  cloudRedisStub: Promise<{[name: string]: Function}>;
+  cloudRedisStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of CloudRedisClient.
@@ -105,28 +110,31 @@ export class CloudRedisClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof CloudRedisClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -136,7 +144,7 @@ export class CloudRedisClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -146,10 +154,10 @@ export class CloudRedisClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      instancePathTemplate: new gaxModule.PathTemplate(
+      instancePathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/locations/{location}/instances/{instance}'
       ),
-      locationPathTemplate: new gaxModule.PathTemplate(
+      locationPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/locations/{location}'
       ),
     };
@@ -159,19 +167,19 @@ export class CloudRedisClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listInstances:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'instances')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'instances')
     };
 
     // This API contains "long-running operations", which return a
     // an Operation object that allows for tracking of the operation,
     // rather than holding a request open.
     const protoFilesRoot = opts.fallback?
-      gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
-      gaxModule.protobuf.loadSync(nodejsProtoPath);
+      this._gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
+      this._gaxModule.protobuf.loadSync(nodejsProtoPath);
 
-    this.operationsClient = gaxModule.lro({
+    this.operationsClient = this._gaxModule.lro({
       auth: this.auth,
-      grpc: 'grpc' in gaxGrpc ? gaxGrpc.grpc : undefined
+      grpc: 'grpc' in this._gaxGrpc ? this._gaxGrpc.grpc : undefined
     }).operationsClient(opts);
     const createInstanceResponse = protoFilesRoot.lookup(
       '.google.cloud.redis.v1beta1.Instance') as gax.protobuf.Type;
@@ -199,34 +207,34 @@ export class CloudRedisClient {
       '.google.protobuf.Any') as gax.protobuf.Type;
 
     this._descriptors.longrunning = {
-      createInstance: new gaxModule.LongrunningDescriptor(
+      createInstance: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         createInstanceResponse.decode.bind(createInstanceResponse),
         createInstanceMetadata.decode.bind(createInstanceMetadata)),
-      updateInstance: new gaxModule.LongrunningDescriptor(
+      updateInstance: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         updateInstanceResponse.decode.bind(updateInstanceResponse),
         updateInstanceMetadata.decode.bind(updateInstanceMetadata)),
-      importInstance: new gaxModule.LongrunningDescriptor(
+      importInstance: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         importInstanceResponse.decode.bind(importInstanceResponse),
         importInstanceMetadata.decode.bind(importInstanceMetadata)),
-      exportInstance: new gaxModule.LongrunningDescriptor(
+      exportInstance: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         exportInstanceResponse.decode.bind(exportInstanceResponse),
         exportInstanceMetadata.decode.bind(exportInstanceMetadata)),
-      failoverInstance: new gaxModule.LongrunningDescriptor(
+      failoverInstance: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         failoverInstanceResponse.decode.bind(failoverInstanceResponse),
         failoverInstanceMetadata.decode.bind(failoverInstanceMetadata)),
-      deleteInstance: new gaxModule.LongrunningDescriptor(
+      deleteInstance: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         deleteInstanceResponse.decode.bind(deleteInstanceResponse),
         deleteInstanceMetadata.decode.bind(deleteInstanceMetadata))
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.cloud.redis.v1beta1.CloudRedis', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -234,15 +242,33 @@ export class CloudRedisClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.cloudRedisStub) {
+      return this.cloudRedisStub;
+    }
 
     // Put together the "service stub" for
     // google.cloud.redis.v1beta1.CloudRedis.
-    this.cloudRedisStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.cloud.redis.v1beta1.CloudRedis') :
+    this.cloudRedisStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.cloud.redis.v1beta1.CloudRedis') :
           // tslint:disable-next-line no-any
-          (protos as any).google.cloud.redis.v1beta1.CloudRedis,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.cloud.redis.v1beta1.CloudRedis,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -261,9 +287,9 @@ export class CloudRedisClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -277,6 +303,8 @@ export class CloudRedisClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.cloudRedisStub;
   }
 
   /**
@@ -389,6 +417,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getInstance(request, options, callback);
   }
 
@@ -473,6 +502,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createInstance(request, options, callback);
   }
   updateInstance(
@@ -546,6 +576,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'instance.name': request.instance!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateInstance(request, options, callback);
   }
   importInstance(
@@ -616,6 +647,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.importInstance(request, options, callback);
   }
   exportInstance(
@@ -684,6 +716,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.exportInstance(request, options, callback);
   }
   failoverInstance(
@@ -749,6 +782,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.failoverInstance(request, options, callback);
   }
   deleteInstance(
@@ -811,6 +845,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteInstance(request, options, callback);
   }
   listInstances(
@@ -905,6 +940,7 @@ export class CloudRedisClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listInstances(request, options, callback);
   }
 
@@ -957,6 +993,7 @@ export class CloudRedisClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listInstances.createStream(
       this._innerApiCalls.listInstances as gax.GaxCall,
       request,
@@ -1058,8 +1095,9 @@ export class CloudRedisClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.cloudRedisStub.then(stub => {
+      return this.cloudRedisStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/redis/test/gapic-cloud_redis-v1beta1.ts.baseline b/baselines/redis/test/gapic-cloud_redis-v1beta1.ts.baseline
index 95ae5616d..acfe49320 100644
--- a/baselines/redis/test/gapic-cloud_redis-v1beta1.ts.baseline
+++ b/baselines/redis/test/gapic-cloud_redis-v1beta1.ts.baseline
@@ -96,12 +96,30 @@ describe('v1beta1.CloudRedisClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new cloudredisModule.v1beta1.CloudRedisClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.cloudRedisStub, undefined);
+        await client.initialize();
+        assert(client.cloudRedisStub);
+    });
+    it('has close method', () => {
+        const client = new cloudredisModule.v1beta1.CloudRedisClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('getInstance', () => {
         it('invokes getInstance without error', done => {
             const client = new cloudredisModule.v1beta1.CloudRedisClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IGetInstanceRequest = {};
             request.name = '';
@@ -125,6 +143,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IGetInstanceRequest = {};
             request.name = '';
@@ -150,6 +170,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.ICreateInstanceRequest = {};
             request.parent = '';
@@ -176,6 +198,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.ICreateInstanceRequest = {};
             request.parent = '';
@@ -205,6 +229,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IUpdateInstanceRequest = {};
             request.instance = {};
@@ -232,6 +258,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IUpdateInstanceRequest = {};
             request.instance = {};
@@ -262,6 +290,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IImportInstanceRequest = {};
             request.name = '';
@@ -288,6 +318,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IImportInstanceRequest = {};
             request.name = '';
@@ -317,6 +349,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IExportInstanceRequest = {};
             request.name = '';
@@ -343,6 +377,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IExportInstanceRequest = {};
             request.name = '';
@@ -372,6 +408,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IFailoverInstanceRequest = {};
             request.name = '';
@@ -398,6 +436,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IFailoverInstanceRequest = {};
             request.name = '';
@@ -427,6 +467,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IDeleteInstanceRequest = {};
             request.name = '';
@@ -453,6 +495,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IDeleteInstanceRequest = {};
             request.name = '';
@@ -482,6 +526,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IListInstancesRequest = {};
             request.parent = '';
@@ -505,6 +551,8 @@ describe('v1beta1.CloudRedisClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.redis.v1beta1.IListInstancesRequest = {};
             request.parent = '';
diff --git a/baselines/showcase/src/v1beta1/echo_client.ts.baseline b/baselines/showcase/src/v1beta1/echo_client.ts.baseline
index ce19047e5..2f2a88f5b 100644
--- a/baselines/showcase/src/v1beta1/echo_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/echo_client.ts.baseline
@@ -40,9 +40,14 @@ export class EchoClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
   operationsClient: gax.OperationsClient;
-  echoStub: Promise<{[name: string]: Function}>;
+  echoStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of EchoClient.
@@ -95,28 +100,31 @@ export class EchoClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof EchoClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -126,7 +134,7 @@ export class EchoClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -136,25 +144,25 @@ export class EchoClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      blueprintPathTemplate: new gaxModule.PathTemplate(
+      blueprintPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}/blueprints/{blueprint}'
       ),
-      roomPathTemplate: new gaxModule.PathTemplate(
+      roomPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}'
       ),
-      roomIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      roomIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}/blurbs/{blurb_id}'
       ),
-      sessionPathTemplate: new gaxModule.PathTemplate(
+      sessionPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}'
       ),
-      testPathTemplate: new gaxModule.PathTemplate(
+      testPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}'
       ),
-      userPathTemplate: new gaxModule.PathTemplate(
+      userPathTemplate: new this._gaxModule.PathTemplate(
         'users/{user_id}'
       ),
-      userIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      userIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'user/{user_id}/profile/blurbs/{blurb_id}'
       ),
     };
@@ -164,27 +172,27 @@ export class EchoClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       pagedExpand:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'responses')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'responses')
     };
 
     // Some of the methods on this service provide streaming responses.
     // Provide descriptors for these.
     this._descriptors.stream = {
-      expand: new gaxModule.StreamDescriptor(gax.StreamType.SERVER_STREAMING),
-      collect: new gaxModule.StreamDescriptor(gax.StreamType.CLIENT_STREAMING),
-      chat: new gaxModule.StreamDescriptor(gax.StreamType.BIDI_STREAMING)
+      expand: new this._gaxModule.StreamDescriptor(gax.StreamType.SERVER_STREAMING),
+      collect: new this._gaxModule.StreamDescriptor(gax.StreamType.CLIENT_STREAMING),
+      chat: new this._gaxModule.StreamDescriptor(gax.StreamType.BIDI_STREAMING)
     };
 
     // This API contains "long-running operations", which return a
     // an Operation object that allows for tracking of the operation,
     // rather than holding a request open.
     const protoFilesRoot = opts.fallback?
-      gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
-      gaxModule.protobuf.loadSync(nodejsProtoPath);
+      this._gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
+      this._gaxModule.protobuf.loadSync(nodejsProtoPath);
 
-    this.operationsClient = gaxModule.lro({
+    this.operationsClient = this._gaxModule.lro({
       auth: this.auth,
-      grpc: 'grpc' in gaxGrpc ? gaxGrpc.grpc : undefined
+      grpc: 'grpc' in this._gaxGrpc ? this._gaxGrpc.grpc : undefined
     }).operationsClient(opts);
     const waitResponse = protoFilesRoot.lookup(
       '.google.showcase.v1beta1.WaitResponse') as gax.protobuf.Type;
@@ -192,14 +200,14 @@ export class EchoClient {
       '.google.showcase.v1beta1.WaitMetadata') as gax.protobuf.Type;
 
     this._descriptors.longrunning = {
-      wait: new gaxModule.LongrunningDescriptor(
+      wait: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         waitResponse.decode.bind(waitResponse),
         waitMetadata.decode.bind(waitMetadata))
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.showcase.v1beta1.Echo', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -207,15 +215,33 @@ export class EchoClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.echoStub) {
+      return this.echoStub;
+    }
 
     // Put together the "service stub" for
     // google.showcase.v1beta1.Echo.
-    this.echoStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.showcase.v1beta1.Echo') :
+    this.echoStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.showcase.v1beta1.Echo') :
           // tslint:disable-next-line no-any
-          (protos as any).google.showcase.v1beta1.Echo,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.showcase.v1beta1.Echo,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -234,9 +260,9 @@ export class EchoClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -250,6 +276,8 @@ export class EchoClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.echoStub;
   }
 
   /**
@@ -351,6 +379,7 @@ export class EchoClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.echo(request, options, callback);
   }
   block(
@@ -410,6 +439,7 @@ export class EchoClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.block(request, options, callback);
   }
 
@@ -434,6 +464,7 @@ export class EchoClient {
     gax.CancellableStream{
     request = request || {};
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.expand(request, options);
   }
 
@@ -471,6 +502,7 @@ export class EchoClient {
         optionsOrCallback = {};
     }
     const options = optionsOrCallback as gax.CallOptions;
+    this.initialize();
     return this._innerApiCalls.collect(null, options, callback);
   }
 
@@ -488,7 +520,8 @@ export class EchoClient {
  */
   chat(
       options?: gax.CallOptions):
-    gax.CancellableStream{
+    gax.CancellableStream {
+    this.initialize();
     return this._innerApiCalls.chat(options);
   }
 
@@ -550,6 +583,7 @@ export class EchoClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.wait(request, options, callback);
   }
   pagedExpand(
@@ -622,6 +656,7 @@ export class EchoClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.pagedExpand(request, options, callback);
   }
 
@@ -658,6 +693,7 @@ export class EchoClient {
     request = request || {};
     options = options || {};
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.pagedExpand.createStream(
       this._innerApiCalls.pagedExpand as gax.GaxCall,
       request,
@@ -900,8 +936,9 @@ export class EchoClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.echoStub.then(stub => {
+      return this.echoStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/showcase/src/v1beta1/identity_client.ts.baseline b/baselines/showcase/src/v1beta1/identity_client.ts.baseline
index b716d4d42..24005f2c0 100644
--- a/baselines/showcase/src/v1beta1/identity_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/identity_client.ts.baseline
@@ -36,8 +36,13 @@ export class IdentityClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  identityStub: Promise<{[name: string]: Function}>;
+  identityStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of IdentityClient.
@@ -90,28 +95,31 @@ export class IdentityClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof IdentityClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -121,7 +129,7 @@ export class IdentityClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -131,25 +139,25 @@ export class IdentityClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      blueprintPathTemplate: new gaxModule.PathTemplate(
+      blueprintPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}/blueprints/{blueprint}'
       ),
-      roomPathTemplate: new gaxModule.PathTemplate(
+      roomPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}'
       ),
-      roomIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      roomIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}/blurbs/{blurb_id}'
       ),
-      sessionPathTemplate: new gaxModule.PathTemplate(
+      sessionPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}'
       ),
-      testPathTemplate: new gaxModule.PathTemplate(
+      testPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}'
       ),
-      userPathTemplate: new gaxModule.PathTemplate(
+      userPathTemplate: new this._gaxModule.PathTemplate(
         'users/{user_id}'
       ),
-      userIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      userIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'user/{user_id}/profile/blurbs/{blurb_id}'
       ),
     };
@@ -159,11 +167,11 @@ export class IdentityClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listUsers:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'users')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'users')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.showcase.v1beta1.Identity', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -171,15 +179,33 @@ export class IdentityClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.identityStub) {
+      return this.identityStub;
+    }
 
     // Put together the "service stub" for
     // google.showcase.v1beta1.Identity.
-    this.identityStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.showcase.v1beta1.Identity') :
+    this.identityStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.showcase.v1beta1.Identity') :
           // tslint:disable-next-line no-any
-          (protos as any).google.showcase.v1beta1.Identity,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.showcase.v1beta1.Identity,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -198,9 +224,9 @@ export class IdentityClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -214,6 +240,8 @@ export class IdentityClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.identityStub;
   }
 
   /**
@@ -315,6 +343,7 @@ export class IdentityClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.createUser(request, options, callback);
   }
   getUser(
@@ -374,6 +403,7 @@ export class IdentityClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getUser(request, options, callback);
   }
   updateUser(
@@ -436,6 +466,7 @@ export class IdentityClient {
     ] = gax.routingHeader.fromParams({
       'user.name': request.user!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateUser(request, options, callback);
   }
   deleteUser(
@@ -495,6 +526,7 @@ export class IdentityClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteUser(request, options, callback);
   }
 
@@ -568,6 +600,7 @@ export class IdentityClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.listUsers(request, options, callback);
   }
 
@@ -605,6 +638,7 @@ export class IdentityClient {
     request = request || {};
     options = options || {};
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listUsers.createStream(
       this._innerApiCalls.listUsers as gax.GaxCall,
       request,
@@ -847,8 +881,9 @@ export class IdentityClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.identityStub.then(stub => {
+      return this.identityStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/showcase/src/v1beta1/messaging_client.ts.baseline b/baselines/showcase/src/v1beta1/messaging_client.ts.baseline
index a1652aedc..204080ee7 100644
--- a/baselines/showcase/src/v1beta1/messaging_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/messaging_client.ts.baseline
@@ -39,9 +39,14 @@ export class MessagingClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
   operationsClient: gax.OperationsClient;
-  messagingStub: Promise<{[name: string]: Function}>;
+  messagingStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of MessagingClient.
@@ -94,28 +99,31 @@ export class MessagingClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof MessagingClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -125,7 +133,7 @@ export class MessagingClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -135,25 +143,25 @@ export class MessagingClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      blueprintPathTemplate: new gaxModule.PathTemplate(
+      blueprintPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}/blueprints/{blueprint}'
       ),
-      roomPathTemplate: new gaxModule.PathTemplate(
+      roomPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}'
       ),
-      roomIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      roomIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}/blurbs/{blurb_id}'
       ),
-      sessionPathTemplate: new gaxModule.PathTemplate(
+      sessionPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}'
       ),
-      testPathTemplate: new gaxModule.PathTemplate(
+      testPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}'
       ),
-      userPathTemplate: new gaxModule.PathTemplate(
+      userPathTemplate: new this._gaxModule.PathTemplate(
         'users/{user_id}'
       ),
-      userIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      userIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'user/{user_id}/profile/blurbs/{blurb_id}'
       ),
     };
@@ -163,29 +171,29 @@ export class MessagingClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listRooms:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'rooms'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'rooms'),
       listBlurbs:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'blurbs')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'blurbs')
     };
 
     // Some of the methods on this service provide streaming responses.
     // Provide descriptors for these.
     this._descriptors.stream = {
-      streamBlurbs: new gaxModule.StreamDescriptor(gax.StreamType.SERVER_STREAMING),
-      sendBlurbs: new gaxModule.StreamDescriptor(gax.StreamType.CLIENT_STREAMING),
-      connect: new gaxModule.StreamDescriptor(gax.StreamType.BIDI_STREAMING)
+      streamBlurbs: new this._gaxModule.StreamDescriptor(gax.StreamType.SERVER_STREAMING),
+      sendBlurbs: new this._gaxModule.StreamDescriptor(gax.StreamType.CLIENT_STREAMING),
+      connect: new this._gaxModule.StreamDescriptor(gax.StreamType.BIDI_STREAMING)
     };
 
     // This API contains "long-running operations", which return a
     // an Operation object that allows for tracking of the operation,
     // rather than holding a request open.
     const protoFilesRoot = opts.fallback?
-      gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
-      gaxModule.protobuf.loadSync(nodejsProtoPath);
+      this._gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
+      this._gaxModule.protobuf.loadSync(nodejsProtoPath);
 
-    this.operationsClient = gaxModule.lro({
+    this.operationsClient = this._gaxModule.lro({
       auth: this.auth,
-      grpc: 'grpc' in gaxGrpc ? gaxGrpc.grpc : undefined
+      grpc: 'grpc' in this._gaxGrpc ? this._gaxGrpc.grpc : undefined
     }).operationsClient(opts);
     const searchBlurbsResponse = protoFilesRoot.lookup(
       '.google.showcase.v1beta1.SearchBlurbsResponse') as gax.protobuf.Type;
@@ -193,14 +201,14 @@ export class MessagingClient {
       '.google.showcase.v1beta1.SearchBlurbsMetadata') as gax.protobuf.Type;
 
     this._descriptors.longrunning = {
-      searchBlurbs: new gaxModule.LongrunningDescriptor(
+      searchBlurbs: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         searchBlurbsResponse.decode.bind(searchBlurbsResponse),
         searchBlurbsMetadata.decode.bind(searchBlurbsMetadata))
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.showcase.v1beta1.Messaging', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -208,15 +216,33 @@ export class MessagingClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.messagingStub) {
+      return this.messagingStub;
+    }
 
     // Put together the "service stub" for
     // google.showcase.v1beta1.Messaging.
-    this.messagingStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.showcase.v1beta1.Messaging') :
+    this.messagingStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.showcase.v1beta1.Messaging') :
           // tslint:disable-next-line no-any
-          (protos as any).google.showcase.v1beta1.Messaging,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.showcase.v1beta1.Messaging,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -235,9 +261,9 @@ export class MessagingClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -251,6 +277,8 @@ export class MessagingClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.messagingStub;
   }
 
   /**
@@ -352,6 +380,7 @@ export class MessagingClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.createRoom(request, options, callback);
   }
   getRoom(
@@ -411,6 +440,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getRoom(request, options, callback);
   }
   updateRoom(
@@ -473,6 +503,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'room.name': request.room!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateRoom(request, options, callback);
   }
   deleteRoom(
@@ -532,6 +563,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteRoom(request, options, callback);
   }
   createBlurb(
@@ -596,6 +628,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createBlurb(request, options, callback);
   }
   getBlurb(
@@ -655,6 +688,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getBlurb(request, options, callback);
   }
   updateBlurb(
@@ -717,6 +751,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'blurb.name': request.blurb!.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.updateBlurb(request, options, callback);
   }
   deleteBlurb(
@@ -776,6 +811,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteBlurb(request, options, callback);
   }
 
@@ -807,6 +843,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.streamBlurbs(request, options);
   }
 
@@ -843,6 +880,7 @@ export class MessagingClient {
         optionsOrCallback = {};
     }
     const options = optionsOrCallback as gax.CallOptions;
+    this.initialize();
     return this._innerApiCalls.sendBlurbs(null, options, callback);
   }
 
@@ -861,7 +899,8 @@ export class MessagingClient {
  */
   connect(
       options?: gax.CallOptions):
-    gax.CancellableStream{
+    gax.CancellableStream {
+    this.initialize();
     return this._innerApiCalls.connect(options);
   }
 
@@ -937,6 +976,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.searchBlurbs(request, options, callback);
   }
   listRooms(
@@ -1009,6 +1049,7 @@ export class MessagingClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.listRooms(request, options, callback);
   }
 
@@ -1046,6 +1087,7 @@ export class MessagingClient {
     request = request || {};
     options = options || {};
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listRooms.createStream(
       this._innerApiCalls.listRooms as gax.GaxCall,
       request,
@@ -1133,6 +1175,7 @@ export class MessagingClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listBlurbs(request, options, callback);
   }
 
@@ -1180,6 +1223,7 @@ export class MessagingClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listBlurbs.createStream(
       this._innerApiCalls.listBlurbs as gax.GaxCall,
       request,
@@ -1422,8 +1466,9 @@ export class MessagingClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.messagingStub.then(stub => {
+      return this.messagingStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/showcase/src/v1beta1/testing_client.ts.baseline b/baselines/showcase/src/v1beta1/testing_client.ts.baseline
index 4a4afa5b4..584cadb85 100644
--- a/baselines/showcase/src/v1beta1/testing_client.ts.baseline
+++ b/baselines/showcase/src/v1beta1/testing_client.ts.baseline
@@ -37,8 +37,13 @@ export class TestingClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  testingStub: Promise<{[name: string]: Function}>;
+  testingStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of TestingClient.
@@ -91,28 +96,31 @@ export class TestingClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof TestingClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -122,7 +130,7 @@ export class TestingClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -132,25 +140,25 @@ export class TestingClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      blueprintPathTemplate: new gaxModule.PathTemplate(
+      blueprintPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}/blueprints/{blueprint}'
       ),
-      roomPathTemplate: new gaxModule.PathTemplate(
+      roomPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}'
       ),
-      roomIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      roomIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'rooms/{room_id}/blurbs/{blurb_id}'
       ),
-      sessionPathTemplate: new gaxModule.PathTemplate(
+      sessionPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}'
       ),
-      testPathTemplate: new gaxModule.PathTemplate(
+      testPathTemplate: new this._gaxModule.PathTemplate(
         'sessions/{session}/tests/{test}'
       ),
-      userPathTemplate: new gaxModule.PathTemplate(
+      userPathTemplate: new this._gaxModule.PathTemplate(
         'users/{user_id}'
       ),
-      userIdBlurbIdPathTemplate: new gaxModule.PathTemplate(
+      userIdBlurbIdPathTemplate: new this._gaxModule.PathTemplate(
         'user/{user_id}/profile/blurbs/{blurb_id}'
       ),
     };
@@ -160,13 +168,13 @@ export class TestingClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listSessions:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'sessions'),
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'sessions'),
       listTests:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'tests')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'tests')
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.showcase.v1beta1.Testing', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -174,15 +182,33 @@ export class TestingClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.testingStub) {
+      return this.testingStub;
+    }
 
     // Put together the "service stub" for
     // google.showcase.v1beta1.Testing.
-    this.testingStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.showcase.v1beta1.Testing') :
+    this.testingStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.showcase.v1beta1.Testing') :
           // tslint:disable-next-line no-any
-          (protos as any).google.showcase.v1beta1.Testing,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.showcase.v1beta1.Testing,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -201,9 +227,9 @@ export class TestingClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -217,6 +243,8 @@ export class TestingClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.testingStub;
   }
 
   /**
@@ -320,6 +348,7 @@ export class TestingClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.createSession(request, options, callback);
   }
   getSession(
@@ -379,6 +408,7 @@ export class TestingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getSession(request, options, callback);
   }
   deleteSession(
@@ -438,6 +468,7 @@ export class TestingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteSession(request, options, callback);
   }
   reportSession(
@@ -499,6 +530,7 @@ export class TestingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.reportSession(request, options, callback);
   }
   deleteTest(
@@ -563,6 +595,7 @@ export class TestingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteTest(request, options, callback);
   }
   verifyTest(
@@ -629,6 +662,7 @@ export class TestingClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.verifyTest(request, options, callback);
   }
 
@@ -699,6 +733,7 @@ export class TestingClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.listSessions(request, options, callback);
   }
 
@@ -733,6 +768,7 @@ export class TestingClient {
     request = request || {};
     options = options || {};
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listSessions.createStream(
       this._innerApiCalls.listSessions as gax.GaxCall,
       request,
@@ -815,6 +851,7 @@ export class TestingClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listTests(request, options, callback);
   }
 
@@ -858,6 +895,7 @@ export class TestingClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listTests.createStream(
       this._innerApiCalls.listTests as gax.GaxCall,
       request,
@@ -1100,8 +1138,9 @@ export class TestingClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.testingStub.then(stub => {
+      return this.testingStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/showcase/test/gapic-echo-v1beta1.ts.baseline b/baselines/showcase/test/gapic-echo-v1beta1.ts.baseline
index 80b20ef95..8d746c59f 100644
--- a/baselines/showcase/test/gapic-echo-v1beta1.ts.baseline
+++ b/baselines/showcase/test/gapic-echo-v1beta1.ts.baseline
@@ -132,12 +132,30 @@ describe('v1beta1.EchoClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new echoModule.v1beta1.EchoClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.echoStub, undefined);
+        await client.initialize();
+        assert(client.echoStub);
+    });
+    it('has close method', () => {
+        const client = new echoModule.v1beta1.EchoClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('echo', () => {
         it('invokes echo without error', done => {
             const client = new echoModule.v1beta1.EchoClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IEchoRequest = {};
             // Mock response
@@ -160,6 +178,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IEchoRequest = {};
             // Mock response
@@ -184,6 +204,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IBlockRequest = {};
             // Mock response
@@ -206,6 +228,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IBlockRequest = {};
             // Mock response
@@ -230,6 +254,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IWaitRequest = {};
             // Mock response
@@ -255,6 +281,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IWaitRequest = {};
             // Mock response
@@ -283,6 +311,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IExpandRequest = {};
             // Mock response
@@ -304,6 +334,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IExpandRequest = {};
             // Mock response
@@ -328,6 +360,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IEchoRequest = {};
             // Mock response
@@ -347,6 +381,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IEchoRequest = {};
             // Mock response
@@ -369,6 +405,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IPagedExpandRequest = {};
             // Mock response
@@ -391,6 +429,8 @@ describe('v1beta1.EchoClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IPagedExpandRequest = {};
             // Mock response
diff --git a/baselines/showcase/test/gapic-identity-v1beta1.ts.baseline b/baselines/showcase/test/gapic-identity-v1beta1.ts.baseline
index 8c1aaa3f4..e3521358c 100644
--- a/baselines/showcase/test/gapic-identity-v1beta1.ts.baseline
+++ b/baselines/showcase/test/gapic-identity-v1beta1.ts.baseline
@@ -78,12 +78,30 @@ describe('v1beta1.IdentityClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new identityModule.v1beta1.IdentityClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.identityStub, undefined);
+        await client.initialize();
+        assert(client.identityStub);
+    });
+    it('has close method', () => {
+        const client = new identityModule.v1beta1.IdentityClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('createUser', () => {
         it('invokes createUser without error', done => {
             const client = new identityModule.v1beta1.IdentityClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateUserRequest = {};
             // Mock response
@@ -106,6 +124,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateUserRequest = {};
             // Mock response
@@ -130,6 +150,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetUserRequest = {};
             request.name = '';
@@ -153,6 +175,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetUserRequest = {};
             request.name = '';
@@ -178,6 +202,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IUpdateUserRequest = {};
             request.user = {};
@@ -202,6 +228,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IUpdateUserRequest = {};
             request.user = {};
@@ -228,6 +256,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteUserRequest = {};
             request.name = '';
@@ -251,6 +281,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteUserRequest = {};
             request.name = '';
@@ -276,6 +308,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListUsersRequest = {};
             // Mock response
@@ -298,6 +332,8 @@ describe('v1beta1.IdentityClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListUsersRequest = {};
             // Mock response
diff --git a/baselines/showcase/test/gapic-messaging-v1beta1.ts.baseline b/baselines/showcase/test/gapic-messaging-v1beta1.ts.baseline
index 2d4a2deed..5cb3657f7 100644
--- a/baselines/showcase/test/gapic-messaging-v1beta1.ts.baseline
+++ b/baselines/showcase/test/gapic-messaging-v1beta1.ts.baseline
@@ -132,12 +132,30 @@ describe('v1beta1.MessagingClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new messagingModule.v1beta1.MessagingClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.messagingStub, undefined);
+        await client.initialize();
+        assert(client.messagingStub);
+    });
+    it('has close method', () => {
+        const client = new messagingModule.v1beta1.MessagingClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('createRoom', () => {
         it('invokes createRoom without error', done => {
             const client = new messagingModule.v1beta1.MessagingClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateRoomRequest = {};
             // Mock response
@@ -160,6 +178,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateRoomRequest = {};
             // Mock response
@@ -184,6 +204,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetRoomRequest = {};
             request.name = '';
@@ -207,6 +229,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetRoomRequest = {};
             request.name = '';
@@ -232,6 +256,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IUpdateRoomRequest = {};
             request.room = {};
@@ -256,6 +282,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IUpdateRoomRequest = {};
             request.room = {};
@@ -282,6 +310,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteRoomRequest = {};
             request.name = '';
@@ -305,6 +335,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteRoomRequest = {};
             request.name = '';
@@ -330,6 +362,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateBlurbRequest = {};
             request.parent = '';
@@ -353,6 +387,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateBlurbRequest = {};
             request.parent = '';
@@ -378,6 +414,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetBlurbRequest = {};
             request.name = '';
@@ -401,6 +439,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetBlurbRequest = {};
             request.name = '';
@@ -426,6 +466,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IUpdateBlurbRequest = {};
             request.blurb = {};
@@ -450,6 +492,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IUpdateBlurbRequest = {};
             request.blurb = {};
@@ -476,6 +520,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteBlurbRequest = {};
             request.name = '';
@@ -499,6 +545,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteBlurbRequest = {};
             request.name = '';
@@ -524,6 +572,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ISearchBlurbsRequest = {};
             request.parent = '';
@@ -550,6 +600,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ISearchBlurbsRequest = {};
             request.parent = '';
@@ -579,6 +631,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IStreamBlurbsRequest = {};
             request.name = '';
@@ -601,6 +655,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IStreamBlurbsRequest = {};
             request.name = '';
@@ -626,6 +682,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IConnectRequest = {};
             // Mock response
@@ -645,6 +703,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IConnectRequest = {};
             // Mock response
@@ -667,6 +727,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListRoomsRequest = {};
             // Mock response
@@ -689,6 +751,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListRoomsRequest = {};
             // Mock response
@@ -713,6 +777,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListBlurbsRequest = {};
             request.parent = '';
@@ -736,6 +802,8 @@ describe('v1beta1.MessagingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListBlurbsRequest = {};
             request.parent = '';
diff --git a/baselines/showcase/test/gapic-testing-v1beta1.ts.baseline b/baselines/showcase/test/gapic-testing-v1beta1.ts.baseline
index 3c27cc0ba..81cb1e560 100644
--- a/baselines/showcase/test/gapic-testing-v1beta1.ts.baseline
+++ b/baselines/showcase/test/gapic-testing-v1beta1.ts.baseline
@@ -78,12 +78,30 @@ describe('v1beta1.TestingClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new testingModule.v1beta1.TestingClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.testingStub, undefined);
+        await client.initialize();
+        assert(client.testingStub);
+    });
+    it('has close method', () => {
+        const client = new testingModule.v1beta1.TestingClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('createSession', () => {
         it('invokes createSession without error', done => {
             const client = new testingModule.v1beta1.TestingClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateSessionRequest = {};
             // Mock response
@@ -106,6 +124,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.ICreateSessionRequest = {};
             // Mock response
@@ -130,6 +150,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetSessionRequest = {};
             request.name = '';
@@ -153,6 +175,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IGetSessionRequest = {};
             request.name = '';
@@ -178,6 +202,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteSessionRequest = {};
             request.name = '';
@@ -201,6 +227,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteSessionRequest = {};
             request.name = '';
@@ -226,6 +254,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IReportSessionRequest = {};
             request.name = '';
@@ -249,6 +279,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IReportSessionRequest = {};
             request.name = '';
@@ -274,6 +306,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteTestRequest = {};
             request.name = '';
@@ -297,6 +331,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IDeleteTestRequest = {};
             request.name = '';
@@ -322,6 +358,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IVerifyTestRequest = {};
             request.name = '';
@@ -345,6 +383,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IVerifyTestRequest = {};
             request.name = '';
@@ -370,6 +410,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListSessionsRequest = {};
             // Mock response
@@ -392,6 +434,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListSessionsRequest = {};
             // Mock response
@@ -416,6 +460,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListTestsRequest = {};
             request.parent = '';
@@ -439,6 +485,8 @@ describe('v1beta1.TestingClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.showcase.v1beta1.IListTestsRequest = {};
             request.parent = '';
diff --git a/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline b/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline
index 414e83565..8306d9229 100644
--- a/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline
+++ b/baselines/texttospeech/src/v1/text_to_speech_client.ts.baseline
@@ -34,8 +34,13 @@ export class TextToSpeechClient {
   private _descriptors: Descriptors = {page: {}, stream: {}, longrunning: {}};
   private _innerApiCalls: {[name: string]: Function};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
-  textToSpeechStub: Promise<{[name: string]: Function}>;
+  textToSpeechStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of TextToSpeechClient.
@@ -88,28 +93,31 @@ export class TextToSpeechClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof TextToSpeechClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -119,14 +127,14 @@ export class TextToSpeechClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
     );
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.cloud.texttospeech.v1.TextToSpeech', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -134,15 +142,33 @@ export class TextToSpeechClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.textToSpeechStub) {
+      return this.textToSpeechStub;
+    }
 
     // Put together the "service stub" for
     // google.cloud.texttospeech.v1.TextToSpeech.
-    this.textToSpeechStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.cloud.texttospeech.v1.TextToSpeech') :
+    this.textToSpeechStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.cloud.texttospeech.v1.TextToSpeech') :
           // tslint:disable-next-line no-any
-          (protos as any).google.cloud.texttospeech.v1.TextToSpeech,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.cloud.texttospeech.v1.TextToSpeech,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -161,9 +187,9 @@ export class TextToSpeechClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -177,6 +203,8 @@ export class TextToSpeechClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.textToSpeechStub;
   }
 
   /**
@@ -287,6 +315,7 @@ export class TextToSpeechClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.listVoices(request, options, callback);
   }
   synthesizeSpeech(
@@ -344,6 +373,7 @@ export class TextToSpeechClient {
       options = optionsOrCallback as gax.CallOptions;
     }
     options = options || {};
+    this.initialize();
     return this._innerApiCalls.synthesizeSpeech(request, options, callback);
   }
 
@@ -354,8 +384,9 @@ export class TextToSpeechClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.textToSpeechStub.then(stub => {
+      return this.textToSpeechStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/texttospeech/test/gapic-text_to_speech-v1.ts.baseline b/baselines/texttospeech/test/gapic-text_to_speech-v1.ts.baseline
index 0ff0b1c89..df81845b3 100644
--- a/baselines/texttospeech/test/gapic-text_to_speech-v1.ts.baseline
+++ b/baselines/texttospeech/test/gapic-text_to_speech-v1.ts.baseline
@@ -78,12 +78,30 @@ describe('v1.TextToSpeechClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new texttospeechModule.v1.TextToSpeechClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.textToSpeechStub, undefined);
+        await client.initialize();
+        assert(client.textToSpeechStub);
+    });
+    it('has close method', () => {
+        const client = new texttospeechModule.v1.TextToSpeechClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('listVoices', () => {
         it('invokes listVoices without error', done => {
             const client = new texttospeechModule.v1.TextToSpeechClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.texttospeech.v1.IListVoicesRequest = {};
             // Mock response
@@ -106,6 +124,8 @@ describe('v1.TextToSpeechClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.texttospeech.v1.IListVoicesRequest = {};
             // Mock response
@@ -130,6 +150,8 @@ describe('v1.TextToSpeechClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.texttospeech.v1.ISynthesizeSpeechRequest = {};
             // Mock response
@@ -152,6 +174,8 @@ describe('v1.TextToSpeechClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.texttospeech.v1.ISynthesizeSpeechRequest = {};
             // Mock response
diff --git a/baselines/translate/src/v3beta1/translation_service_client.ts.baseline b/baselines/translate/src/v3beta1/translation_service_client.ts.baseline
index 57328a1e8..282c8d5e7 100644
--- a/baselines/translate/src/v3beta1/translation_service_client.ts.baseline
+++ b/baselines/translate/src/v3beta1/translation_service_client.ts.baseline
@@ -36,9 +36,14 @@ export class TranslationServiceClient {
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
   operationsClient: gax.OperationsClient;
-  translationServiceStub: Promise<{[name: string]: Function}>;
+  translationServiceStub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of TranslationServiceClient.
@@ -91,28 +96,31 @@ export class TranslationServiceClient {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof TranslationServiceClient).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -122,7 +130,7 @@ export class TranslationServiceClient {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -132,10 +140,10 @@ export class TranslationServiceClient {
     // identifiers to uniquely identify resources within the API.
     // Create useful helper objects for these.
     this._pathTemplates = {
-      glossaryPathTemplate: new gaxModule.PathTemplate(
+      glossaryPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/locations/{location}/glossaries/{glossary}'
       ),
-      locationPathTemplate: new gaxModule.PathTemplate(
+      locationPathTemplate: new this._gaxModule.PathTemplate(
         'projects/{project}/locations/{location}'
       ),
     };
@@ -145,19 +153,19 @@ export class TranslationServiceClient {
     // pages). Denote the keys used for pagination and results.
     this._descriptors.page = {
       listGlossaries:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'glossaries')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', 'glossaries')
     };
 
     // This API contains "long-running operations", which return a
     // an Operation object that allows for tracking of the operation,
     // rather than holding a request open.
     const protoFilesRoot = opts.fallback?
-      gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
-      gaxModule.protobuf.loadSync(nodejsProtoPath);
+      this._gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
+      this._gaxModule.protobuf.loadSync(nodejsProtoPath);
 
-    this.operationsClient = gaxModule.lro({
+    this.operationsClient = this._gaxModule.lro({
       auth: this.auth,
-      grpc: 'grpc' in gaxGrpc ? gaxGrpc.grpc : undefined
+      grpc: 'grpc' in this._gaxGrpc ? this._gaxGrpc.grpc : undefined
     }).operationsClient(opts);
     const batchTranslateTextResponse = protoFilesRoot.lookup(
       '.google.cloud.translation.v3beta1.BatchTranslateResponse') as gax.protobuf.Type;
@@ -173,22 +181,22 @@ export class TranslationServiceClient {
       '.google.cloud.translation.v3beta1.DeleteGlossaryMetadata') as gax.protobuf.Type;
 
     this._descriptors.longrunning = {
-      batchTranslateText: new gaxModule.LongrunningDescriptor(
+      batchTranslateText: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         batchTranslateTextResponse.decode.bind(batchTranslateTextResponse),
         batchTranslateTextMetadata.decode.bind(batchTranslateTextMetadata)),
-      createGlossary: new gaxModule.LongrunningDescriptor(
+      createGlossary: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         createGlossaryResponse.decode.bind(createGlossaryResponse),
         createGlossaryMetadata.decode.bind(createGlossaryMetadata)),
-      deleteGlossary: new gaxModule.LongrunningDescriptor(
+      deleteGlossary: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         deleteGlossaryResponse.decode.bind(deleteGlossaryResponse),
         deleteGlossaryMetadata.decode.bind(deleteGlossaryMetadata))
     };
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         'google.cloud.translation.v3beta1.TranslationService', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -196,15 +204,33 @@ export class TranslationServiceClient {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.translationServiceStub) {
+      return this.translationServiceStub;
+    }
 
     // Put together the "service stub" for
     // google.cloud.translation.v3beta1.TranslationService.
-    this.translationServiceStub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('google.cloud.translation.v3beta1.TranslationService') :
+    this.translationServiceStub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('google.cloud.translation.v3beta1.TranslationService') :
           // tslint:disable-next-line no-any
-          (protos as any).google.cloud.translation.v3beta1.TranslationService,
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).google.cloud.translation.v3beta1.TranslationService,
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -223,9 +249,9 @@ export class TranslationServiceClient {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -239,6 +265,8 @@ export class TranslationServiceClient {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.translationServiceStub;
   }
 
   /**
@@ -410,6 +438,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.translateText(request, options, callback);
   }
   detectLanguage(
@@ -503,6 +532,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.detectLanguage(request, options, callback);
   }
   getSupportedLanguages(
@@ -593,6 +623,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.getSupportedLanguages(request, options, callback);
   }
   getGlossary(
@@ -653,6 +684,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.getGlossary(request, options, callback);
   }
 
@@ -769,6 +801,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.batchTranslateText(request, options, callback);
   }
   createGlossary(
@@ -831,6 +864,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.createGlossary(request, options, callback);
   }
   deleteGlossary(
@@ -892,6 +926,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'name': request.name || '',
     });
+    this.initialize();
     return this._innerApiCalls.deleteGlossary(request, options, callback);
   }
   listGlossaries(
@@ -979,6 +1014,7 @@ export class TranslationServiceClient {
     ] = gax.routingHeader.fromParams({
       'parent': request.parent || '',
     });
+    this.initialize();
     return this._innerApiCalls.listGlossaries(request, options, callback);
   }
 
@@ -1030,6 +1066,7 @@ export class TranslationServiceClient {
       'parent': request.parent || '',
     });
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.listGlossaries.createStream(
       this._innerApiCalls.listGlossaries as gax.GaxCall,
       request,
@@ -1131,8 +1168,9 @@ export class TranslationServiceClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.translationServiceStub.then(stub => {
+      return this.translationServiceStub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/baselines/translate/test/gapic-translation_service-v3beta1.ts.baseline b/baselines/translate/test/gapic-translation_service-v3beta1.ts.baseline
index 63224dcf4..a73aadfea 100644
--- a/baselines/translate/test/gapic-translation_service-v3beta1.ts.baseline
+++ b/baselines/translate/test/gapic-translation_service-v3beta1.ts.baseline
@@ -96,12 +96,30 @@ describe('v3beta1.TranslationServiceClient', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new translationserviceModule.v3beta1.TranslationServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.translationServiceStub, undefined);
+        await client.initialize();
+        assert(client.translationServiceStub);
+    });
+    it('has close method', () => {
+        const client = new translationserviceModule.v3beta1.TranslationServiceClient({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
     describe('translateText', () => {
         it('invokes translateText without error', done => {
             const client = new translationserviceModule.v3beta1.TranslationServiceClient({
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.ITranslateTextRequest = {};
             request.parent = '';
@@ -125,6 +143,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.ITranslateTextRequest = {};
             request.parent = '';
@@ -150,6 +170,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IDetectLanguageRequest = {};
             request.parent = '';
@@ -173,6 +195,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IDetectLanguageRequest = {};
             request.parent = '';
@@ -198,6 +222,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IGetSupportedLanguagesRequest = {};
             request.parent = '';
@@ -221,6 +247,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IGetSupportedLanguagesRequest = {};
             request.parent = '';
@@ -246,6 +274,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IGetGlossaryRequest = {};
             request.name = '';
@@ -269,6 +299,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IGetGlossaryRequest = {};
             request.name = '';
@@ -294,6 +326,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IBatchTranslateTextRequest = {};
             request.parent = '';
@@ -320,6 +354,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IBatchTranslateTextRequest = {};
             request.parent = '';
@@ -349,6 +385,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.ICreateGlossaryRequest = {};
             request.parent = '';
@@ -375,6 +413,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.ICreateGlossaryRequest = {};
             request.parent = '';
@@ -404,6 +444,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IDeleteGlossaryRequest = {};
             request.name = '';
@@ -430,6 +472,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IDeleteGlossaryRequest = {};
             request.name = '';
@@ -459,6 +503,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IListGlossariesRequest = {};
             request.parent = '';
@@ -482,6 +528,8 @@ describe('v3beta1.TranslationServiceClient', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             const request: protosTypes.google.cloud.translation.v3beta1.IListGlossariesRequest = {};
             request.parent = '';
diff --git a/templates/typescript_gapic/src/$version/$service_client.ts.njk b/templates/typescript_gapic/src/$version/$service_client.ts.njk
index 8b0781e08..36fb2c5e0 100644
--- a/templates/typescript_gapic/src/$version/$service_client.ts.njk
+++ b/templates/typescript_gapic/src/$version/$service_client.ts.njk
@@ -45,11 +45,16 @@ export class {{ service.name }}Client {
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   {%- endif %}
   private _terminated = false;
+  private _opts: ClientOptions;
+  private _gaxModule: typeof gax | typeof gax.fallback;
+  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
+  private _protos: {};
+  private _defaults: {[method: string]: gax.CallSettings};
   auth: gax.GoogleAuth;
 {%- if (service.longRunning.length > 0) %}
   operationsClient: gax.OperationsClient;
 {%- endif %}
-  {{ service.name.toCamelCase() }}Stub: Promise<{[name: string]: Function}>;
+  {{ service.name.toCamelCase() }}Stub?: Promise<{[name: string]: Function}>;
 
   /**
    * Construct an instance of {{ service.name }}Client.
@@ -102,28 +107,31 @@ export class {{ service.name }}Client {
     // If we are in browser, we are already using fallback because of the
     // "browser" field in package.json.
     // But if we were explicitly requested to use fallback, let's do it now.
-    const gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
+    this._gaxModule = !isBrowser && opts.fallback ? gax.fallback : gax;
 
     // Create a `gaxGrpc` object, with any grpc-specific options
     // sent to the client.
     opts.scopes = (this.constructor as typeof {{ service.name }}Client).scopes;
-    const gaxGrpc = new gaxModule.GrpcClient(opts);
+    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
+
+    // Save options to use in initialize() method.
+    this._opts = opts;
 
     // Save the auth object to the client, for use by other methods.
-    this.auth = (gaxGrpc.auth as gax.GoogleAuth);
+    this.auth = (this._gaxGrpc.auth as gax.GoogleAuth);
 
     // Determine the client header string.
     const clientHeader = [
-      `gax/${gaxModule.version}`,
+      `gax/${this._gaxModule.version}`,
       `gapic/${version}`,
     ];
     if (typeof process !== 'undefined' && 'versions' in process) {
       clientHeader.push(`gl-node/${process.versions.node}`);
     } else {
-      clientHeader.push(`gl-web/${gaxModule.version}`);
+      clientHeader.push(`gl-web/${this._gaxModule.version}`);
     }
     if (!opts.fallback) {
-      clientHeader.push(`grpc/${gaxGrpc.grpcVersion}`);
+      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
@@ -133,7 +141,7 @@ export class {{ service.name }}Client {
     // For browsers, pass the JSON content.
 
     const nodejsProtoPath = path.join(__dirname, '..', '..', 'protos', 'protos.json');
-    const protos = gaxGrpc.loadProto(
+    this._protos = this._gaxGrpc.loadProto(
       opts.fallback ?
         require("../../protos/protos.json") :
         nodejsProtoPath
@@ -145,7 +153,7 @@ export class {{ service.name }}Client {
     // Create useful helper objects for these.
     this._pathTemplates = {
 {%- for template in service.pathTemplates %}
-      {{ template.name.toCamelCase() }}PathTemplate: new gaxModule.PathTemplate(
+      {{ template.name.toCamelCase() }}PathTemplate: new this._gaxModule.PathTemplate(
         '{{ template.pattern }}'
       ),
 {%- endfor %}
@@ -162,7 +170,7 @@ export class {{ service.name }}Client {
 {%- for method in service.paging %}
       {{- pagingJoiner() }}
       {{ method.name.toCamelCase() }}:
-          new gaxModule.PageDescriptor('pageToken', 'nextPageToken', '{{ method.pagingFieldName.toCamelCase() }}')
+          new this._gaxModule.PageDescriptor('pageToken', 'nextPageToken', '{{ method.pagingFieldName.toCamelCase() }}')
 {%- endfor %}
     };
 {%- endif %}
@@ -175,7 +183,7 @@ export class {{ service.name }}Client {
 {%- set streamingJoiner = joiner() %}
 {%- for method in service.streaming %}
       {{- streamingJoiner() }}
-      {{ method.name.toCamelCase() }}: new gaxModule.StreamDescriptor(gax.StreamType.{{ method.streaming }})
+      {{ method.name.toCamelCase() }}: new this._gaxModule.StreamDescriptor(gax.StreamType.{{ method.streaming }})
 {%- endfor %}
     };
 {%- endif %}
@@ -185,12 +193,12 @@ export class {{ service.name }}Client {
     // an Operation object that allows for tracking of the operation,
     // rather than holding a request open.
     const protoFilesRoot = opts.fallback?
-      gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
-      gaxModule.protobuf.loadSync(nodejsProtoPath);
+      this._gaxModule.protobuf.Root.fromJSON(require("../../protos/protos.json")) :
+      this._gaxModule.protobuf.loadSync(nodejsProtoPath);
 
-    this.operationsClient = gaxModule.lro({
+    this.operationsClient = this._gaxModule.lro({
       auth: this.auth,
-      grpc: 'grpc' in gaxGrpc ? gaxGrpc.grpc : undefined
+      grpc: 'grpc' in this._gaxGrpc ? this._gaxGrpc.grpc : undefined
     }).operationsClient(opts);
 
 {%- for method in service.longRunning %}
@@ -204,7 +212,7 @@ export class {{ service.name }}Client {
 {%- set longRunningJoiner = joiner() %}
 {%- for method in service.longRunning %}
       {{- longRunningJoiner() }}
-      {{ method.name.toCamelCase() }}: new gaxModule.LongrunningDescriptor(
+      {{ method.name.toCamelCase() }}: new this._gaxModule.LongrunningDescriptor(
         this.operationsClient,
         {{ method.name.toCamelCase() }}Response.decode.bind({{ method.name.toCamelCase() }}Response),
         {{ method.name.toCamelCase() }}Metadata.decode.bind({{ method.name.toCamelCase() }}Metadata))
@@ -213,7 +221,7 @@ export class {{ service.name }}Client {
 {%- endif %}
 
     // Put together the default options sent with requests.
-    const defaults = gaxGrpc.constructSettings(
+    this._defaults = this._gaxGrpc.constructSettings(
         '{{ api.naming.protoPackage }}.{{ service.name }}', gapicConfig as gax.ClientConfig,
         opts.clientConfig || {}, {'x-goog-api-client': clientHeader.join(' ')});
 
@@ -221,15 +229,33 @@ export class {{ service.name }}Client {
     // of calling the API is handled in `google-gax`, with this code
     // merely providing the destination and request information.
     this._innerApiCalls = {};
+  }
+
+  /**
+   * Initialize the client.
+   * Performs asynchronous operations (such as authentication) and prepares the client.
+   * This function will be called automatically when any class method is called for the
+   * first time, but if you need to initialize it before calling an actual method,
+   * feel free to call initialize() directly.
+   *
+   * You can await on this method if you want to make sure the client is initialized.
+   *
+   * @returns {Promise} A promise that resolves to an authenticated service stub.
+   */
+  initialize() {
+    // If the client stub promise is already initialized, return immediately.
+    if (this.{{ service.name.toCamelCase() }}Stub) {
+      return this.{{ service.name.toCamelCase() }}Stub;
+    }
 
     // Put together the "service stub" for
     // {{api.naming.protoPackage}}.{{ service.name }}.
-    this.{{ service.name.toCamelCase() }}Stub = gaxGrpc.createStub(
-        opts.fallback ?
-          (protos as protobuf.Root).lookupService('{{api.naming.protoPackage}}.{{ service.name }}') :
+    this.{{ service.name.toCamelCase() }}Stub = this._gaxGrpc.createStub(
+        this._opts.fallback ?
+          (this._protos as protobuf.Root).lookupService('{{api.naming.protoPackage}}.{{ service.name }}') :
           // tslint:disable-next-line no-any
-          (protos as any).{{api.naming.protoPackage}}.{{ service.name }},
-        opts) as Promise<{[method: string]: Function}>;
+          (this._protos as any).{{api.naming.protoPackage}}.{{ service.name }},
+        this._opts) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -254,9 +280,9 @@ export class {{ service.name }}Client {
           throw err;
         });
 
-      const apiCall = gaxModule.createApiCall(
+      const apiCall = this._gaxModule.createApiCall(
         innerCallPromise,
-        defaults[methodName],
+        this._defaults[methodName],
         this._descriptors.page[methodName] ||
             this._descriptors.stream[methodName] ||
             this._descriptors.longrunning[methodName]
@@ -270,6 +296,8 @@ export class {{ service.name }}Client {
         return apiCall(argument, callOptions, callback);
       };
     }
+
+    return this.{{ service.name.toCamelCase() }}Stub;
   }
 
   /**
@@ -373,6 +401,7 @@ export class {{ service.name }}Client {
       options = optionsOrCallback as gax.CallOptions;
     }
     {{ util.buildHeaderRequestParam(method) }}
+    this.initialize();
     return this._innerApiCalls.{{ method.name.toCamelCase() }}(request, options, callback);
   }
 {%- endfor %}
@@ -383,7 +412,8 @@ export class {{ service.name }}Client {
  */
   {{ method.name.toCamelCase() }}(
       options?: gax.CallOptions):
-    gax.CancellableStream{
+    gax.CancellableStream {
+    this.initialize();
     return this._innerApiCalls.{{ method.name.toCamelCase() }}(options);
   }
 {%- elif method.serverStreaming %}
@@ -396,6 +426,7 @@ export class {{ service.name }}Client {
     gax.CancellableStream{
     request = request || {};
     {{ util.buildHeaderRequestParam(method) }}
+    this.initialize();
     return this._innerApiCalls.{{ method.name.toCamelCase() }}(request, options);
   }
 {%- elif method.clientStreaming %}
@@ -426,6 +457,7 @@ export class {{ service.name }}Client {
         optionsOrCallback = {};
     }
     const options = optionsOrCallback as gax.CallOptions;
+    this.initialize();
     return this._innerApiCalls.{{ method.name.toCamelCase() }}(null, options, callback);
   }
 {%- endif %}
@@ -471,6 +503,7 @@ export class {{ service.name }}Client {
       options = optionsOrCallback as gax.CallOptions;
     }
     {{ util.buildHeaderRequestParam(method) }}
+    this.initialize();
     return this._innerApiCalls.{{ method.name.toCamelCase() }}(request, options, callback);
   }
 {%- endfor %}
@@ -518,6 +551,7 @@ export class {{ service.name }}Client {
       options = optionsOrCallback as gax.CallOptions;
     }
     {{ util.buildHeaderRequestParam(method) }}
+    this.initialize();
     return this._innerApiCalls.{{ method.name.toCamelCase() }}(request, options, callback);
   }
 
@@ -531,6 +565,7 @@ export class {{ service.name }}Client {
     request = request || {};
     {{ util.buildHeaderRequestParam(method) }}
     const callSettings = new gax.CallSettings(options);
+    this.initialize();
     return this._descriptors.page.{{ method.name.toCamelCase() }}.createStream(
       this._innerApiCalls.{{ method.name.toCamelCase() }} as gax.GaxCall,
       request,
@@ -586,8 +621,9 @@ export class {{ service.name }}Client {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
+    this.initialize();
     if (!this._terminated) {
-      return this.{{ service.name.toCamelCase() }}Stub.then(stub => {
+      return this.{{ service.name.toCamelCase() }}Stub!.then(stub => {
         this._terminated = true;
         stub.close();
       });
diff --git a/templates/typescript_gapic/test/gapic-$service-$version.ts.njk b/templates/typescript_gapic/test/gapic-$service-$version.ts.njk
index 84f3e4969..e1a7755cb 100644
--- a/templates/typescript_gapic/test/gapic-$service-$version.ts.njk
+++ b/templates/typescript_gapic/test/gapic-$service-$version.ts.njk
@@ -143,6 +143,22 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
         });
         assert(client);
     });
+    it('has initialize method and supports deferred initialization', async () => {
+        const client = new {{ service.name.toLowerCase() }}Module.{{ api.naming.version }}.{{ service.name }}Client({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        assert.strictEqual(client.{{ service.name.toCamelCase() }}Stub, undefined);
+        await client.initialize();
+        assert(client.{{ service.name.toCamelCase() }}Stub);
+    });
+    it('has close method', () => {
+        const client = new {{ service.name.toLowerCase() }}Module.{{ api.naming.version }}.{{ service.name }}Client({
+            credentials: { client_email: 'bogus', private_key: 'bogus' },
+            projectId: 'bogus',
+        });
+        client.close();
+    });
 {%- for method in service.simpleMethods %}
     describe('{{ method.name.toCamelCase() }}', () => {
         it('invokes {{ method.name.toCamelCase() }} without error', done => {
@@ -150,6 +166,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -172,6 +190,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -198,6 +218,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -223,6 +245,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -253,6 +277,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -274,6 +300,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -300,6 +328,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -319,6 +349,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -343,6 +375,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response
@@ -365,6 +399,8 @@ describe('{{ api.naming.version }}.{{ service.name }}Client', () => {
                 credentials: {client_email: 'bogus', private_key: 'bogus'},
                 projectId: 'bogus',
             });
+            // Initialize client before mocking
+            client.initialize();
             // Mock request
             {{ util.initRequestWithHeaderParam(method) }}
             // Mock response