Marquee names highlight semifinals action at the 2012 Western & Southern Open at the Lindner Family Tennis Center in Mason, Ohio near Cincinnati on Saturday.
After advancing in Friday's quarterfinals, Novak Djokovic will face Juan Martin Del Potro on center court at 1 p.m. ET. About 30 minutes after the conclusion of that match, Roger Federer will take on unranked Stanislas Wawrinka.
Fresh off gold medal performances at the 2012 London Summer Olympics, No. 2 seed Serena Williams was defeated in her quarterfinal match against fifth-seeded Angelique Kerber, but sister Venus Williams advanced and will square off against No. 9 seed Na Li at 7 p.m. ET. The other women's semifinal will pit Kerber against Petra Kvitova.