U.K., August 3: Serena Williams will face world number one Victoria Azarenka in the semi-finals of the Olympic women’s singles after beating Caroline Wozniacki.

The American, who has two doubles gold medals, won 6-0 6-3 as Azarenka of Belarus beat Angelique Kerber 6-4 7-5.

Russia’s Maria Sharapova overcame Kim Clijsters and plays compatriot Maria Kirilenko, who upset Petra Kvitova.

In the men’s last four, Roger Federer meets Juan Martin del Potro and Novak Djokovic takes on Andy Murray.

Swiss top seed Federer posted a 6-4 7-6 (7-5) victory over American John Isner to give himself an Olympic medal shot for the first time.