Second-seeded Amelie Mauresmo [Images] of France [Images] easily advanced to the quarter-finals of the $1.3 million Rogers Cup on Thursday, defeating Spain's Conchita Martinez 6-0, 6-2, but injuries to other seeded players continued.

Also advancing was fourth-seeded Justine Henin-Hardenne of Belgium, who eliminated China's Jie Zheng 6-2, 6-4, but third-seeded Russian Svetlana Kuznetsova [Images] was hampered for her entire match by back pain and was eliminated by Argentina's Gisela Dulko 7-6 (3), 7-6 (8).

Ana Ivanovic [Images] of Serbia and Montenegro, the 12th seed, withdrew from the tournament Thursday due to a strained right chest muscle, resulting in a walkover for Belgium's Kim Clijsters [Images], the number seven seed.

The injuries and the latest withdrawal came as a disappointment to tournament organizers, as seven top 20 ranked players have already withdrawn from the event.

Fifth-seeded Serena Williams [Images] of the United States, top-seeded Russian star Maria Sharapova [Images] and Venus Williams [Images] of the U.S., the ninth-ranked player in the world, are among the players who have withdrawn from the tournament at one point or another.

The injuries and withdrawls, combined with an easy match Thursday, suits Mauresmo, the defending champion, just fine.

"Obviously, just not spending too much time on the court is an advantage when you play these kinds of tournaments, when you have to go out every day," Mauresmo said.

The extent of the injuries at the tournament is evident for one of the quarter-finals, where Clijsters will meet 14th-seeded Flavia Pennetta [Images], who advanced when Serena Williams also pulled out on Wednesday.

"It hurt during the doubles match (Wednesday) night," Ivanovic said in a statement. "The best thing I can do now is to get treatment and hopefully be ready for the U.S. Open."

Kuznetsova looked like she would have to quit her match in the first set as she was obviously playing in severe pain. But she stuck it out and eventually lost the second set in a 10-8 tie-breaker.

"It's hurting very much. I think I should have stopped playing," Kuznetsova admitted.

In another match marred by an injury, Russian Nadia Petrova [Images] advanced when Li Na [Images] of China had to quit their match due to an injured ankle. Petrova was leading 6-3, 3-0 when the match was stopped.

In other matches Thursday, ninth-seeded Russian Anastasia Myskina [Images] also battled injury but managed to beat Shinobu Asagoe of Japan [Images] 7-6 (5), 7-5 and Nicole Vaidisova [Images] of the Czech Republic beat countrywoman Hana Sromova 6-2, 6-2.

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