PARIS -- Jo-Wilfried Tsonga has pulled out of the U.S. Open with a knee injury.

The eighth-ranked Frenchman hasn't played since June 26 when he was forced to retire from his second-round match at Wimbledon against Ernests Gulbis. Tsonga says on his website Thursday that his left knee needs more time to recover and he hopes to be ready for the Moselle Open in Metz, France, in September.

The 28-year-old Tsonga already missed the Rogers Cup in Montreal earlier this month due to the injury.

The U.S. Open, the year's final Grand Slam tournament, starts on Aug. 26.