For the third time in his career, Novak Djokovic has won the ATP World Tour Finals to end the season. Novak Djokovic defeated Rafael Nadal in straight sets, 6-3, 6-4, on Monday in London. It was a great display of tennis from the world's No. 2. Even if he won't have the No. 1 ranking at the end of the 2013 season, Djokovic made a strong case that he's the best tennis player in the world. He was so controlled on Monday night and was almost robotic in the way he deflected Nadal's best shots.