Rafael Nadal, knocked out of Wimbledon in the second round last week, is to take two weeks off because of tendinitis in his knee.
The Spaniard will miss a charity match against world number one Novak Djokovic in Madrid's Bernabeu stadium on July 14 but hopes, however, to have fully recovered in time for the July 27-August 12 Olympics in London.
"I want to apologise to all, in particular to the fans that had already purchased a ticket to such a good cause, but unfortunately we won't be able to play for the moment that match in Madrid," he said.
"The doctors have been checking my knee and I suffer a tendinitis which will have me away from any practice or matches for 15 days, which makes it impossible to play with Novak Djokovic as we'd expected and announced.
"I was with my doctors on Monday and started already my treatment with the goal to be ready for the London Olympic Games and represent Spain once again."
Nadal, the world number two, added: "I will now work on my rehab as well as taking some short holidays to resume my practice in 15 days."