WIMBLEDON: Williams sisters, Venus and Serena, and five-time champion Roger Federer advanced to the quarter-finals of the Wimbledon today. Venus advanced when opponent Ana Ivanovic retired one game into the second set today. Vevnus, seeking her sixth Wimbledon title, led 6-1, 0-1 when Ivanovic was forced to quit. The Williams sisters remained on course for a rematch of last year’s all-family final, which Venus won. Serena, seeking her third Wimbledon title, advanced by beating Daniela Hantuchova 6-3, 6-1. Ivanovic took a 10-minute break during the first game of the second set to have her left thigh taped by a trainer. She returned for two more points and hit a service winner to take the game. But she then began crying as she walked to her chair and told the umpire she was retiring. No. 3-seeded Venus dominated from the start, taking a 5-0 lead before Ivanovic finally won a game 27 minutes into the match. Venus came into the match having won 29 consecutive sets at Wimbledon, the longest such streak since Martina Navratilova won 40 in a row in 1982-85. Former No 1 Ivanovic still hasn’t reached a Grand Slam quarter-final since winning the 2008 French Open. Earlier, fourth-seeded Elena Dementieva became the first player to reach the quarter-finals by beating fellow Russian Elena Vesnina 6-1, 6-3. Dementieva faced little resistance in the first set and never faced a break point in the match. She sealed the win by breaking for the second time in the second set, converting her second match point. Dementieva is playing her 11th straight Wimbledon and reached the semi-finals last year. American 17-year-old Melanie Oudin’s surprising run ended when she lost to No 11-seeded Agnieszka Radwanska of Poland 6-4, 7-5. The 124th-ranked Oudin, the last remaining qualifier, flubbed an easy volley to lose the first set, and she was up a break in the second set. Oudin, making her Wimbledon debut this year, pulled the biggest upset in the first week by beating former No 1 Jelena Jankovic. Oudin was the youngest American to reach the women’s fourth round at Wimbledon since Jennifer Capriati was a quarter-finalist in 1993. Also, No 8 Victoria Azarenka beat No 10 Nadia Petrova 7-6 (5), 2-6, 6-3. On the men’s side, Federer reached the quarter-finals with a 6-4, 7-6 (7/5), 7-6 (7/5) win over Sweden’s Robin Soderling. Federer takes on either Croatia’s Ivo Karlovic or Spain’s Fernando Verdasco for a place in the semi-finals. Likewise, No 24 Tommy Haas beat No 29 Igor Andreev 7-6 (8), 6-4, 6-4.