?Roger Federer of Switzerland returns a shot to Fernando Verdasco of Spain during their ATP World Tour Finals first round tennis match in London, capital of Britain, Nov. 22, 2009. Federer won the match 2-1. [Xinhua/Zeng Yi]

World No. 1 Roger Federer came from behind to defeat seventh-seeded Spanish Fernando Verdasco 4-6, 7-5and 6-1 at the ATP World Tour Finals on Sunday.

"I was down a set, and only the second set was I able to sort of get the ball into play, find my range, find my rhythm. I think this is also when I started to feel like I had chances," said Federer.

The 28-year-old Swiss opened his first battle at the London's O2 stadium with double faults then lost the first game at love. The Spanish world No. 8 never gave Federer a chance to break before finishing the first set at 6-4.

Roger Federer of Switzerland returns a shot to Fernando Verdasco of Spain during their ATP World Tour Finals first round tennis match in London, capital of Britain, Nov. 22, 2009. Federer won the match 2-1. [Xinhua/Zeng Yi]

Verdasco, 26, making his debut at the season ending finale, continued to play strongly in the second set but failed to hold onto his sixth serve before faded unexpectedly 6-1 in the third set.

Although four titles this year seemed not amazing enough for Federer, to some extent, he did achieve another peak in his career by claiming victory in the French Open in his 11th attempt and became the sixth man in history to win all four Grand Slam titles.