WIMBLEDON, England (AP) -To prepare for his Wimbledon semifinal against Andy Murray, Rafael Nadal got in a little soccer practice.
The top-ranked Spaniard dashed around the practice court Thursday kicking and heading tennis balls, showing no sign that his troublesome knees were bothering him.
His uncle and coach, Toni Nadal, said the player's knees are in good shape going into Friday's match against the fourth-seeded Murray.
"His game hasn't changed," Toni Nadal said. "We'll try to play like it's 2008."
That was the year Nadal won the Wimbledon title, beating Roger Federer in an epic five-set final.
Nadal skipped Wimbledon last year because of tendinitis in both knees. Last week, he said that his right knee had flared recently and that he would skip Spain's Davis Cup quarterfinal against France to get treatment ahead of the U.S. hardcourt season.
Toni Nadal said his nephew's knees would not deter him from a run at another Wimbledon championship.
"He is in good (shape)," Toni Nadal said. "He just needs to play the big points without mistakes."
The coach said Nadal is ready to go five sets if necessary.
"But I don't think that will happen," he said.
If Nadal's tendinitis is chronic, doctors say he could face regular bouts of inflammation that requires time off to recover.
"His knees will probably be his undoing at some point, or prevent him from becoming even more amazing than he already is," said Dr. Anders Cohen, chief of neurosurgery at the Brooklyn Hospital Center and a former doctor for the U.S. Open.
Cohen hasn't treated Nadal or seen his medical records, but said the player's muscular build - which means he is carrying more weight than most players - and aggressive game is a perfect combination to put stress on the knees.
Cohen said it was possible Nadal could be battling other joint problems, like worn-out cartilage or even a degenerative knee problem. Still, Cohen said the fact that Nadal was playing so well this year suggested he had recovered from tendinitis.
Tendinitis happens when the tendon connecting the muscle to the bone becomes inflamed after being overly stressed - like after the quick sprints, jumps and lunges often seen on the tennis court. The body usually tries to treat inflammation with the blood supply, which brings in nutrients and takes out waste material.
Tendons are not well connected to the blood system and take much longer to heal than muscles, which have a steady blood flow. Even with medication and physical therapy, recovering from tendinitis requires time off.
Other tennis players such as Brazilian Gustavo Kuerten and Australian Pat Rafter have had their careers cut short after having joint problems after too much wear and tear.