WIMBLEDON, England — Venus Williams advanced to the quarterfinals at Wimbledon when opponent Ana Ivanovic retired Monday one game into the second set.

American 17-year-old Melanie Oudin was eliminated.

Williams led 6-1, 0-1 when Ivanovic called it quits.

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, but after hitting a service winner to take the game, she began crying as she walked to her chair and told the umpire she was retiring.

Oudin, a qualifier from Marietta, Ga., lost to No. 11-seeded Agnieszka Radwanska, 6-4, 7-5.

Missed chances hurt Oudin. She flubbed an easy volley to lose the first set, and she was up a break in the second set before her surprising Wimbledon came to an end.

Oudin pulled the biggest upset in the first week of the tournament 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 quarterfinalist in 1993.

Williams, seeking her sixth Wimbledon title, took a 5-0 lead before Ivanovic won a game 27 minutes into the match. Former No. 1 Ivanovic hasn’t reached a Grand Slam quarterfinal since winning the 2008 French Open.

Second-seeded Serena Williams, fourth-seeded Elena Dementieva and No. 8 Victoria Azarenka also advanced.

Williams beat Daniela Hantuchova 6-3, 6-1, losing just two points on her first serve and breaking Hantuchova five times to complete the win in 56 minutes.

Williams is looking for her third Wimbledon title after winning here in 2002-03. She lost last year’s final to her sister.

Azarenka battled her way into the quarterfinals with a hard-fought 7-6 (5), 2-6, 6-3 victory over Russia’s Nadia Petrova.

The eighth seed, the first woman from Belarus to reach the last eight at Wimbledon since Natasha Zvereva in 1998, will have to raise her game to stand a chance against Serena Williams in the last eight.

An abysmal first set was awash with unforced errors, both players each losing their serve three times apiece before Azarenka, yowling with effort on every point, squeaked home 7-5 in a tight tiebreak.

Petrova, treated at the end of the set with ice packs to counteract the heat, came back with guns blazing to even the match but could not maintain the pressure in the decider, and Azarenka wrapped it up after 2 hours, 25 minutes.

Dementieva beat 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 consecutive Wimbledon tournament and reached the semifinals last year.

Information from The Associated Press and Reuters was used in this report. – ESPN