Video: Novak Djokovic happy with 'mental state' at 2013 US Open
Novak Djokovic reacts to his dominant fourth round victory over Marcel Granollers (6-3, 6-0, 6-0). Djokovic and Youzhny will meet in the semifinals after he defeated Lleyton Hewitt in five sets (6-3, 3-6, 6-7, 6-4, 7-5).