Federer wins, Venus loses at Olympics

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LONDON, Aug. 1 (UPI) -- Top seeds Roger Federer and Victoria Azarenka reached the quarterfinals of the Olympic tennis tournament Wednesday while Venus Williams was eliminated.

Federer, seeking a gold medal for Switzerland, downed Denis Istomin of Uzbekistan 7-5, 6-3 a month after winning the Wimbledon title.

His quarterfinal opponent will be American John Isner, who got past Janko Tipsarevic 7-5, 7-6 (16-14).

Azarenka had to work to survive against Nadia Petrova of Russia 7-6 (8-6), 6-4. She will now meet Angelique Kerber of Germany, who won two tiebreaks in defeating Williams 7-6 (7-5), 7-6 (7-5).

On a day of British success around other Olympic venues, Andy Murray added to it with his 4-6, 6-1, 6-4 victory over Marcos Baghdatis of Cyprus. Nicolas Almagro of Spain will await Murray in the quarterfinals after knocking off Steve Darcis of Belgium 7-5, 6-3.

One day after surviving a 3-hour third set in his win over Canadian Milos Raonic, Jo-Wilfried Tsonga of France knocked off Feliciano Lopez of Spain 7-6 (7-5), 6-4.

Tsonga will take on Novak Djokovic of Serbia in the quarterfinals after the second-seeded player rallied to dismiss Lleyton Hewitt of Australia 4-6, 7-5, 6-1.

In the women's draw, Serena Williams routed Vera Zvonareva of Russia 6-1, 6-0. Isner and Serena Williams are the only Americans left in the singles portion of the tournament.

Kim Clijsters of Belgium, Marina Kirilenko of Russia, 2010 Wimbledon champion Petra Kvitova of the Czech Republic and Russian Maria Sharapova also reached the quarterfinals.