French Open champion Rafael Nadal
French Open champion Rafael Nadal does not know when he will be fit to play tennis again, but insists he has "plenty of years ahead" in the sport.
The 11-time Grand Slam champion is recovering from a knee injury and has not played since Wimbledon in June.
"I will return to the court when I feel that the knee no longer gives me any pain, whether that is in two weeks or in three or four," said the Spaniard.
According to the BBC, Nadal, 26, has slipped to fourth in the world rankings.
He is currently sidelined with a partial tear of the patella [kneecap] tendon and an inflammation of the Hoffa's fat pad [soft tissue behind the patella], and was forced to miss the Olympic Games and the US Open.
It remains doubtful whether he will be fit for the ATP World Tour Finals in London or Spain's Davis Cup final against the Czech Republic, both in November.
Nadal's last match was a shock five-set defeat by Czech world number 100, Lukas Rosol, at Wimbledon on 28 June and he has yet to return to the court as he continues his rehabilitation in the gym.
"I am working as much as I can," he said. "I am doing everything they tell me to every day and the truth is that right now things are going well, more or less. The only thing is that I need a bit more time.
"We'll see how things develop in the next few weeks but my priority is to recover well - not quickly, but well - obviously as soon as possible, but the main thing is to have the certainty that you are fine when you do return."
Nadal has struggled with knee problems previously and was unable to defend his Wimbledon title in 2009 because of tendinitis.
This year he reached the Australian Open final in January, before winning his seventh French Open title in June, and aims to be competing for another Grand Slam title in Melbourne in the new year.
"What I hope for is to be ready to compete again for everything I want to compete for, like I did in the first six months of the year," he said. "That is what I will try to achieve. It's what I will fight for and work every day.
"I am 26 years old and I am confident I have plenty of years ahead. What I want is to recover well and to continue enjoying tennis and competition, which is what makes me happy right now."
The Spaniard also had a word for Andy Murray after the Scot won the US Open earlier this month to claim his first Grand Slam title.