PARIS (Reuters) - World number 13 Gael Monfils has pulled out of the French Open because of a right knee injury, the French tennis federation (FFT) said on Thursday.

The injury-prone Frenchman, who lost to Roger Federer in the quarter-finals at the claycourt grand slam event last year, will be out of action for three weeks.

Monfils has been struggling with his form in recent weeks and suffered a shock defeat to unheralded American Brian Baker in the second round at Nice on Wednesday.

The French Open starts at Roland Garros on Sunday.

(Reporting by Gregory Blachier; Editing by Mark Meadows)