Experts fear for Nadal as his knee problem returns

Rafa Nadal is upbeat about his future despite being forced to pull out of the Australian Open with yet another a knee injury. But some experts fear for his chances of ever getting back to his best.

The world number two retired in the third set of his quarter final with Andy Murray on Tuesday, but says he does not anticipate a long lay-off. It is thought that the problem is a recurrence of the tendontis that undermined his French Open campaign and forced him to miss last year's Wimbledon.

After the match Nadal said: "I think it's going to be OK." But was unimpressed when asked if it would affect his future. "Don't start with these questions right now," he begged.

The full extent of the problem should become clear when Nadal returns home to be assessed by Spanish Tennis Federation doctor Angel Ruiz-Cotorro on Friday, but one expert says that the problem could be long-term.

Australian doctor Peter Brukner told the Melbourne Age that the fact it was a recurrence of an old injury was a worry. "Tendonitis can be career threatening, certainly," he said. "The worry is that he might need an extended period out of the game, given that the nine weeks [he took off last year] didn't really seem to do the trick. He might need three to six months out of the game."

Last year tennis coach Sven Groneveld, who has worked with Ana Ivanovic and Fernando Verdasco, said that he has never known a player to be so badly afflicted at such a young age as Nadal. Others have suggested that growing up playing on hard surfraces had left his knees in the sort of state a player of 33 would expect.

Nadal admitted that he had felt "a similar thing to what I had last year" while trying to chase down a drop shot in the latter stages of the second set. But he added that he had chosen discretion over valour when throwing in the towel. He said he did not want to repeat the error of last year when he played on with the problem. "I go to the limit, but not cross the limit," he explained.

The Spaniard also praised Andy Murray - who was well ahead in the match when Nadal retired - and tipped him to win the tournament. "He has a really good chance because he's playing really well," he said. "I think he deserves to win his first Grand Slam, and he gonna do it." ·