Mikel Sanchez, the surgeon who treated Rafael Nadal's knees earlier this year, tells Marca that the injury has healed but the physical toll of training and playing could cause it to re-occur at some stage.

"The tendon is cured -- wider, with a different physical appearance, but cured," said Sanchez. "At the moment I'm not doing anything, but will probably have to return.

"He's going to continue at the same rhythm and there is a risk that his tendons will degenerate again. That is why you cannot say this is a permanent treatment. Plus, it could occur in other tendons such as the Achilles."

Nadal received injections of enriched blood plasma in his knees in May and July. After winning Monte Carlo, he missed Barcelona to undergo treatment. Since then, he has lost only three matches and won five tournaments, which includes the French Open, Wimbledon and the U.S. Open.

"It was incredible that he could keep playing with his knees like they were," said Sanchez of Nadal's condition earlier this year. "He has to understand that as he gets older he has to have a balance."