Novak Djokovic defeats Tomas Berdych 6-3, 6-3 in Group A at the ATP World Tour Finals. Djokovic's relatively simple victory followed Andy Murray and Roger Federer's posted easy victories on Sunday, which meant the first three opening matches of the event had had little drama.

But Rafael Nadal and Andy Roddick changed the trend with a tight 3-6, 7-6(5), 6-4 contest in Monday's second match, with Roddick up a set and a break before Nadal came back to win.

"I was a little bit lucky tonight," said Nadal, who won his first match at the O2 Arena after going 0-3 last year without winning a set. "I started the match a little bit nervous. Five weeks without playing and on a tough surface for me it was always going to be difficult against one of the best servers in the world. I think I was very close to lose today."

Roddick was up a break at 2-1 in the second set but was unable to hang on. and then saw the Spaniard break him in the fifth game of the deciding set.

"The difference was he found his range on his forehand in the second and third sets," Roddick said. He was able to find his defensive forehand more and wasn't spraying it. That changed the dimension of the rallies a bit."