diff --git a/includes/validation/class-amp-validation-manager.php b/includes/validation/class-amp-validation-manager.php
index ac0da4705c3..9900ee389ce 100644
--- a/includes/validation/class-amp-validation-manager.php
+++ b/includes/validation/class-amp-validation-manager.php
@@ -486,14 +486,32 @@ class_exists( 'WP_Block_Type_Registry' )
 	/**
 	 * Handle save_post action to queue re-validation of the post on the frontend.
 	 *
+	 * This is intended to only apply to post edits made in the classic editor.
+	 *
+	 * @see AMP_Validation_Manager::get_amp_validity_rest_field() The method responsible for validation post changes via Gutenberg.
 	 * @see AMP_Validation_Manager::validate_queued_posts_on_frontend()
 	 *
 	 * @param int $post_id Post ID.
 	 */
 	public static function handle_save_post_prompting_validation( $post_id ) {
+		global $pagenow;
 		$post = get_post( $post_id );
 
+		$is_classic_editor_post_save = (
+			isset( $_SERVER['REQUEST_METHOD'] )
+			&&
+			'POST' === $_SERVER['REQUEST_METHOD']
+			&&
+			'post.php' === $pagenow
+			&&
+			isset( $_POST['post_ID'] ) // WPCS: csrf ok.
+			&&
+			intval( $_POST['post_ID'] ) === (int) $post_id // WPCS: csrf ok.
+		);
+
 		$should_validate_post = (
+			$is_classic_editor_post_save
+			&&
 			is_post_type_viewable( $post->post_type )
 			&&
 			! wp_is_post_autosave( $post )
@@ -531,7 +549,10 @@ function( $post ) {
 
 		$validation_posts = array();
 
-		// @todo Only validate the first and then queue the rest in WP Cron?
+		/*
+		 * It is unlikely that there will be more than one post in the array.
+		 * For the bulk recheck action, see AMP_Invalid_URL_Post_Type::handle_bulk_action().
+		 */
 		foreach ( $posts as $post ) {
 			$url = amp_get_permalink( $post->ID );
 			if ( ! $url ) {
diff --git a/tests/validation/test-class-amp-validation-manager.php b/tests/validation/test-class-amp-validation-manager.php
index 1b7457035ff..b978eb43707 100644
--- a/tests/validation/test-class-amp-validation-manager.php
+++ b/tests/validation/test-class-amp-validation-manager.php
@@ -293,19 +293,31 @@ public function test_add_validation_error_sourcing_gutenberg() {
 	 * @covers AMP_Validation_Manager::validate_queued_posts_on_frontend()
 	 */
 	public function test_handle_save_post_prompting_validation_and_validate_queued_posts_on_frontend() {
+		$_SERVER['REQUEST_METHOD'] = 'POST';
+		$GLOBALS['pagenow']        = 'post.php'; // WPCS: override ok.
+
 		register_post_type( 'secret', array( 'public' => false ) );
-		$secret = $this->factory()->post->create_and_get( array( 'post_type' => 'secret' ) );
+		$secret           = $this->factory()->post->create_and_get( array( 'post_type' => 'secret' ) );
+		$_POST['post_ID'] = $secret->ID;
 		AMP_Validation_Manager::handle_save_post_prompting_validation( $secret->ID );
 		$this->assertFalse( has_action( 'shutdown', array( 'AMP_Validation_Manager', 'validate_queued_posts_on_frontend' ) ) );
 		$this->assertEmpty( AMP_Validation_Manager::validate_queued_posts_on_frontend() );
 
-		$auto_draft = $this->factory()->post->create_and_get( array( 'post_status' => 'auto-draft' ) );
+		$auto_draft       = $this->factory()->post->create_and_get( array( 'post_status' => 'auto-draft' ) );
+		$_POST['post_ID'] = $auto_draft->ID;
 		AMP_Validation_Manager::handle_save_post_prompting_validation( $auto_draft->ID );
 		$this->assertFalse( has_action( 'shutdown', array( 'AMP_Validation_Manager', 'validate_queued_posts_on_frontend' ) ) );
 		$this->assertEmpty( AMP_Validation_Manager::validate_queued_posts_on_frontend() );
 
+		// Testing without $_POST context.
 		$post = $this->factory()->post->create_and_get( array( 'post_type' => 'post' ) );
 		AMP_Validation_Manager::handle_save_post_prompting_validation( $post->ID );
+		$this->assertFalse( has_action( 'shutdown', array( 'AMP_Validation_Manager', 'validate_queued_posts_on_frontend' ) ) );
+
+		// Test success.
+		$post = $this->factory()->post->create_and_get( array( 'post_type' => 'post' ) );
+		$_POST['post_ID'] = $post->ID;
+		AMP_Validation_Manager::handle_save_post_prompting_validation( $post->ID );
 		$this->assertEquals( 10, has_action( 'shutdown', array( 'AMP_Validation_Manager', 'validate_queued_posts_on_frontend' ) ) );
 
 		add_filter( 'pre_http_request', function() {
@@ -314,6 +326,8 @@ public function test_handle_save_post_prompting_validation_and_validate_queued_p
 		$results = AMP_Validation_Manager::validate_queued_posts_on_frontend();
 		$this->assertArrayHasKey( $post->ID, $results );
 		$this->assertInstanceOf( 'WP_Error', $results[ $post->ID ] );
+
+		unset( $GLOBALS['pagenow'] );
 	}
 
 	/**