LONDON, Nov. 28 (Xinhua) -- Swiss world No. 2 Roger Federer defeated archrival Rafael Nadal in three sets, becoming the final winner of the ATP World Tour Finals on Sunday. It's the fifth time that the 16 Grand Slam titles holder was crowned at the season finale. "It's fantastic. I'm really thrilled the way I played all week," said Federer. "I'm just really happy the way I was able to finish the season in style, playing some of my best tennis, really saving the best for last." Federer, 29, has been in stunning form by winning all three group matches...