PARIS, Nov. 3 -- Year-end world No. 1 Rafael Nadal announced his withdrawal from ATP 1000 Paris Masters here on Friday.

"Of course, it's a very hard decision for me," Nadal told a press conference. "Pulling out from any event is tough, but especially here from Paris. As I said a lot of times, it's the most important city in my career, without doubt."

Nadal secured season-ending world No. 1 following his victory over South Korean talent Chung Hyeon, before he overcame Uruguay's Pablo Cuevas in round of 16.

However, the Spanish tennis ace felt pain in his right knee before Thursday's decider, and had bandage on his right knee when returning to the court.

"Yesterday the pain during the match was too much, but it was not the moment to stop. I don't like to stop in the middle of the match.

"And especially during the match, thinking that I have some hours in between to do some treatment, that's what I did yesterday with the doctor here," explained Nadal.

"But being honest with the tournament, my opponents and myself, the way that I am today. I don't see myself playing three more matches here.

"I did one treatment yesterday night to try to play today, but it's impossible to go on court like yesterday," he added.

Nadal's previous best record at the Paris Masters came in 2007, when he finished runner-up behind Argentina's David Nalbandian.

"It's a tough situation, a sad one. But I'm calm that I came here, I tried my best, I did all the things I had to do to try to play this event," he commented.

Nadal emphasized that it was not the right moment to think about the ATP Finals in London in less than two weeks.

"I am enough sad to pull out from here. I feel like home here. It's very tough today for me. So it's not the right day to talk about London.

"The only thing I'm going to say is, that I'm going to do my treatment, do my best to play in London," he said.

Following Nadal's withdrawal, the Serbian qualifier Filip Krajinovic set up a clash with John Isner of the United States after making his first semi-final appearance at a ATP 1000 event.

Ninth-seeded Isner upset Juan Martin del Potro in full sets, and could clinch last spot at ATP Finals if he won the title in Paris. On the other hand, the Argentine Potro was set to miss the Finals.

PARIS, Nov. 3 -- Year-end world No. 1 Rafael Nadal announced his withdrawal from ATP 1000 Paris Masters here on Friday.

"Of course, it's a very hard decision for me," Nadal told a press conference. "Pulling out from any event is tough, but especially here from Paris. As I said a lot of times, it's the most important city in my career, without doubt."

Nadal secured season-ending world No. 1 following his victory over South Korean talent Chung Hyeon, before he overcame Uruguay's Pablo Cuevas in round of 16.

However, the Spanish tennis ace felt pain in his right knee before Thursday's decider, and had bandage on his right knee when returning to the court.

"Yesterday the pain during the match was too much, but it was not the moment to stop. I don't like to stop in the middle of the match.

"And especially during the match, thinking that I have some hours in between to do some treatment, that's what I did yesterday with the doctor here," explained Nadal.

"But being honest with the tournament, my opponents and myself, the way that I am today. I don't see myself playing three more matches here.

"I did one treatment yesterday night to try to play today, but it's impossible to go on court like yesterday," he added.

Nadal's previous best record at the Paris Masters came in 2007, when he finished runner-up behind Argentina's David Nalbandian.

"It's a tough situation, a sad one. But I'm calm that I came here, I tried my best, I did all the things I had to do to try to play this event," he commented.

Nadal emphasized that it was not the right moment to think about the ATP Finals in London in less than two weeks.

"I am enough sad to pull out from here. I feel like home here. It's very tough today for me. So it's not the right day to talk about London.

"The only thing I'm going to say is, that I'm going to do my treatment, do my best to play in London," he said.

Following Nadal's withdrawal, the Serbian qualifier Filip Krajinovic set up a clash with John Isner of the United States after making his first semi-final appearance at a ATP 1000 event.

Ninth-seeded Isner upset Juan Martin del Potro in full sets, and could clinch last spot at ATP Finals if he won the title in Paris. On the other hand, the Argentine Potro was set to miss the Finals.