Defending champion Caroline Wozniacki earned a spot in the quarterfinals of the China Open tennis tournament in Beijing with a victory Thursday. Wozniacki, the No. 1-ranked women\'s player, defeated Kaia Kanepi 6-3, 7-5 (6-3). Wozniacki broke up a tight first set by winning the last three games and was serving for the match at 5-4 of the second when Kanepi forced the tiebreaker. Wozniacki won five of the last six points in taking the match. No. 13-seeded Anastasia Pavlyuchenkova advanced to the quarterfinals with a walkover when second-seeded Victoria Azarenka withdrew due to a right foot injury. Azarenka said the injury had been bothering her since last week in Tokyo and that she hoped to return to the court next month in Luxembourg. No. 11-seeded Agnieszka Radwanska took a 6-4, 6-2 decision from Sofia Arvidsson in the other match Thursday involving a seeded player. Radwanska, who had her serve broken five times, piled up eight breaks in nine receiving games. Also Thursday, Flavia Pennetta topped Dominika Cibulkova 6-1, 4-6, 6-4; Maria Kirilenko beat Tamira Paszek 6-1, 6-2; and Monica Niculescu survived a 2 1/2-hour battle with Virginie Razzano 4-6, 6-1, 6-2. Wozniacki has drawn Pennetta and Radwanska plays Ana Ivanovic in one half of the quarterfinals Friday. Kirilenko meets Niculescu and Pavlyuchenkova goes against ninth-seeded Andrea Petkovic in the other.