The top-ranked Spaniard said in a statement Tuesday that after two days of medical tests in Barcelona he has decided to try physical therapy to prepare for the tournament, which starts June 22.
"I am going to give my 200 percent to be ready for the most important tournament in the world," Nadal said. "I will not go out and play, especially on the Wimbledon Centre Court, if I am not 100 percent ready to play.
"I have two difficult weeks ahead of me, especially because I won't be doing what I like doing most, which is to play tennis."
Nadal withdrew from a grass-court warmup event at Queen's Club this week. His 31-match winning streak at the French Open ended with a fourth-round loss to eventual finalist Robin Soderling.
"I have been playing with pain on my knees for some months now and I simply can't go on like this," Nadal said. "The pain was limiting certain movements in my body, which affected me mentally as well."
Spanish Tennis Federation physician Dr. Angel Ruiz-Cotorro said Nadal has tendinitis in both knees.
"His treatment will involve oral anti-inflammatories, physiotherapy, as well as muscular exercises for both quadriceps," Ruiz-Cotorro said.
Copyright 2009 The Associated Press.