An injury has forced Rafael Nadal out of theU.S. Open.
The No. 3-ranked tennis player is battling a knee injury.
The tournament, which is the final major of the year, starts on Aug. 27.
Nadal earlier withdrew from the Western and Southern Open in Cincinnati that starts this week. He also did not compete in the Olympics.
Nadal lost in the second round at Wimbledon and cited tendonitis when he withdrew from a charity match against World No. 2-ranked Novak Djokovic at Real Madrid's Bernabeu Stadium.
Nadal battled chronic knee issues in 2009.
source: The Chicago Tribune
