Defending champion Novak Djokovic set up an enticing final against Rafael Nadal with a 6-3, 6-3 victory Sunday over Stanislas Wawrinka at the ATP World Tour Finals. Nadal ended Roger Federer's hopes of finishing a disappointing season on a high note, defeating the six-time champion 7-5, 6-3 in the other semifinal. Unbeaten in his round-robin matches this week, the second-seeded Djokovic extended his winning streak to 21 matches since losing in the U.S. Open final to Nadal. More...