diff --git a/src/Transport/GrpcTransport.php b/src/Transport/GrpcTransport.php
index 9d1e9af0e..1d8869aab 100644
--- a/src/Transport/GrpcTransport.php
+++ b/src/Transport/GrpcTransport.php
@@ -60,6 +60,8 @@ class GrpcTransport extends BaseStub implements TransportInterface
     use GrpcSupportTrait;
     use ServiceAddressTrait;
 
+    private BaseStub $stub;
+
     /**
      * @param string $hostname
      * @param array $opts
@@ -86,7 +88,7 @@ public function __construct(string $hostname, array $opts, Channel $channel = nu
             );
         }
 
-        parent::__construct($hostname, $opts, $channel);
+        $this->stub = new BaseStub($hostname, $opts, $channel);
     }
 
     /**
@@ -177,7 +179,6 @@ public function startBidiStreamingCall(Call $call, array $options)
      */
     public function startClientStreamingCall(Call $call, array $options)
     {
-
         $this->verifyUniverseDomain($options);
 
         return new ClientStream(
@@ -254,6 +255,11 @@ function () use ($unaryCall, $options, &$promise) {
         return $promise;
     }
 
+    public function close()
+    {
+        $this->stub->close();
+    }
+
     private function verifyUniverseDomain(array $options)
     {
         if (isset($options['credentialsWrapper'])) {
@@ -283,4 +289,62 @@ private static function loadClientCertSource(callable $clientCertSource)
     {
         return call_user_func($clientCertSource);
     }
+
+    /** FOR TESTING */
+
+    /**
+     * @param string $method
+     * @param array $arguments
+     * @param callable $deserialize
+     */
+    protected function _simpleRequest(
+        $method,
+        $arguments,
+        $deserialize,
+        array $metadata = [],
+        array $options = []
+    ) {
+        return $this->stub->_simpleRequest($method, $arguments, $deserialize, $metadata, $options);
+    }
+
+    /**
+     * @param string $method
+     * @param callable $deserialize
+     */
+    protected function _clientStreamRequest(
+        $method,
+        $deserialize,
+        array $metadata = [],
+        array $options = []
+    ) {
+        return $this->stub->_clientStreamRequest($method, $deserialize, $metadata, $options);
+    }
+
+    /**
+     * @param string $method
+     * @param array $arguments
+     * @param callable $deserialize
+     */
+    protected function _serverStreamRequest(
+        $method,
+        $arguments,
+        $deserialize,
+        array $metadata = [],
+        array $options = []
+    ) {
+        return $this->stub->_serverStreamRequest($method, $arguments, $deserialize, $metadata, $options);
+    }
+
+    /**
+     * @param string $method
+     * @param callable $deserialize
+     */
+    protected function _bidiRequest(
+        $method,
+        $deserialize,
+        array $metadata = [],
+        array $options = []
+    ) {
+        return $this->stub->_bidiRequest($method, $deserialize, $metadata, $options);
+    }
 }
diff --git a/tests/Tests/Unit/Transport/GrpcTransportTest.php b/tests/Tests/Unit/Transport/GrpcTransportTest.php
index 9d8e37d70..6ab705746 100644
--- a/tests/Tests/Unit/Transport/GrpcTransportTest.php
+++ b/tests/Tests/Unit/Transport/GrpcTransportTest.php
@@ -505,21 +505,24 @@ public function buildInvalidData()
      */
     public function testExperimentalInterceptors($callType, $interceptor)
     {
+        $mockCallInvoker = new MockCallInvoker($this->buildMockCallForInterceptor($callType));
+
         $transport = new GrpcTransport(
             'example.com',
             [
-                'credentials' => ChannelCredentials::createInsecure()
+                'credentials' => ChannelCredentials::createInsecure(),
             ],
             null,
             [$interceptor]
         );
 
-        $mockCallInvoker = new MockCallInvoker($this->buildMockCallForInterceptor($callType));
+        $r1 = new \ReflectionProperty(GrpcTransport::class, 'stub');
+        $r1->setAccessible(true);
 
-        $r = new \ReflectionProperty(BaseStub::class, 'call_invoker');
-        $r->setAccessible(true);
-        $r->setValue(
-            $transport,
+        $r2 = new \ReflectionProperty(BaseStub::class, 'call_invoker');
+        $r2->setAccessible(true);
+        $r2->setValue(
+            $r1->getValue($transport),
             $mockCallInvoker
         );