Novak Djokovic could meet Andy Murray in the semifinals at U.S. Open . Andy Murray and Serena Williams face a potential quarterfinal showdown in U.S. . Serena Williams begins against another grand slam winner , Rafael Nadal . Former winner Maria Sharapova pulled out of the tournament with a shoulder injury .
Novak Djokovic could meet Andy Murray in the semifinals at the U.S. Open . Roger Federer and Rafael Nadal face a potential quarterfinal showdown in New York . Serena Williams begins against another grand slam winner , Francesca Schiavone . Former winner Maria Sharapova pulled out of the tournament with a shoulder injury .