Venus Williams of the U.S. waits on the return from Magdalena Rybarikova of Slovakia with her left knee wrapped during their match at the U.S. Open tennis tournament in New York, September 4, 2009. REUTERS/Jeff Zelevansky (UNITED STATES SPORT TENNIS)

Guillermo Canas of Argentina hits a return to Tommy Robredo of Spain during their Master Tennis Burgos match in Burgos, northern Spain July 27, 2009. REUTERS/Felix Ordonez (SPAIN SPORT TENNIS)