As we can load third party component model like this:
Loader::import('joomla.application.component.model');
JLoader::import('modelname', JPATH_ROOT.'/components/com_componentname/models');
$model = JModelLegacy::getInstance( 'modelname', 'ComponentNameModel' );
Is there any similar way to load sub-controller of a third party component and execute a method in it?