Federer out of French Open

Roger Federer has undergone surgery to resolve a longstanding knee problem and said Thursday he would be out of action until after the French Open.

The 20-time Grand Slam winner revealed on his Facebook account that he underwent surgery in Switzerland on Wednesday and would miss a string of tournaments including the May 24-June 7 French Open.

"As a result, I will miss Dubai, India Wells, Bogota, Miami and the French Open," he said.

"I can't wait to be back playing again soon, see you on grass!"