Defending champion Novak Djokovic defeated six-time winner Roger Federer 6-4 6-7 (2) 6-2 at the ATP World Tour Finals, keeping alive his chances of overtaking Rafael Nadal in the race for the year-end No. 1 spot.
Playing his first round robin match at the elite tournament this year, Djokovic extended his winning streak to 18 matches after capturing his sixth title of the season last week in Paris, where he defeated Federer in the semifinals.
Djokovic is trying to finish No. 1 for the third year in a row but Nadal, who eased past David Ferrer 6-3 6-2 yesterday, needs only one more win in London to be guaranteed the top spot.
This 31st encounter between the two rivals -- a remake of last year's final -- produced a somewhat disjointed match laced with unforced errors and flashes of brilliant tennis leaving both players looking exhausted toward the end of the match yesterday.
Federer and Djokovic easily held their serve until the ninth game when the Serb found himself 15-30 down.
A double fault gave Federer his first break point but the former World No. 1 sent a forehand wide on the next point before Djokovic took the next two points to hold his serve.
The Serb earned two break points in the next game with a superb backhand return. The cheering from the legion of Swiss supporters packed in the stands did not help Federer as he fluffed a forehand to lose the set.
