Nadal pulls out of ATP Finals

After losing to Belgian David Goffin 7-6 (5), 6-7, 6-4 in his first match at the ATP World Tour Finals in London on Monday, men's world number one Rafael Nadal said he was pulling out of the tournament with a knee injury.

"My season is finished," the Spaniard told reporters after the match. "My commitment was to try. I've missed this event too many times in my career."

Read more: Alexander Zverev beats Marin Cilic, Roger Federer wins opener

The injury had already forced Nadal, 31, to pull out from the Paris Masters earlier this month. The season-ending tournament, which consists of the top eight players from the tennis season, is the only major event Nadal has never won despite qualifying for it 13 consecutive times.

The Spaniard's withdrawal is a disappointing end for an otherwise positive season. The injury-prone tennis star reached the final of the Australian Open before winning the French Open and US Open, performances which helped him return to the top of the men's tennis rankings for the first time in four years.

With Nadal dropping out, Roger Federer, ranked second in the world and the winner of this year's Australian Open and Wimbledon, is the presumed favorite in the ATP Finals. The Swiss tennis star faces Germany's Alexander Zverev in the second round of group play on Tuesday.

Pablo Carreno Busta, one of the two alternates for the tournament, will replace his compatriot Nadal in the tournament. Busta must defeat Grigor Dimitrov of Hungary and Dominic Thiem of Austria in order to qualify for the semifinals. Dimitrov defeated Thiem 6-3, 5-7, 7-5 on Tuesday as the first round of group play came to a close.

dv/aw (AP, AFP, Reuters)