Spring - how to inject concrete interface implementation?

I need to inject by @Autowired concrete implementation of a service class.

Service interface:

public interface PostService {
...
}

Implementation:

@Service("postServiceImpl")
public class PostServiceImpl implements PostService {
...
}

And now I want to inject postServiceImpl to my controller - because I need to use one method from the implementation, that is not in the interface:

@Autowired
@Qualifier("postServiceImpl")
private PostServiceImpl postService;

I get NoSuchBeanDefinitionException with the following message:

No qualifying bean of type [ (...) .PostServiceImpl] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency.

when I change the field in my controller to:

private PostService postService

it works, but I can't use a specific method from PostServiceImpl.