diff --git a/starlette/routing.py b/starlette/routing.py
index 9a2134957..90387f75d 100644
--- a/starlette/routing.py
+++ b/starlette/routing.py
@@ -421,9 +421,12 @@ def matches(self, scope: Scope) -> typing.Tuple[Match, Scope]:
             path = scope["path"]
             root_path = scope.get("route_root_path", scope.get("root_path", ""))
             route_path = scope.get("route_path", re.sub(r"^" + root_path, "", path))
-            match = self.path_regex.match(route_path)
-            if match:
-                matched_params = match.groupdict()
+            mount_match = self.path_regex.match(route_path)
+            path_match = self.routes == [] or any(
+                [route.matches(scope)[0] == Match.FULL for route in self.routes]
+            )
+            if mount_match and path_match:
+                matched_params = mount_match.groupdict()
                 for key, value in matched_params.items():
                     matched_params[key] = self.param_convertors[key].convert(value)
                 remaining_path = "/" + matched_params.pop("path")