With top seeds Jelena Jankovic and Serena Williams waiting in the wings to test their ailing knees, Samantha Stosur and Melinda Czink notched upset wins at the WTA hardcourt tournament in Los Angeles on Monday.

Hungary's Czink, a lucky loser who only made it into the draw after Svetlana Kuznetsova withdrew with a knee injury, ousted France's 13th-seeded Virginie Razzano 6-3, 6-3.

Australia's Stosur steamrolled 12th-seeded Israeli Shahar Peer 6-1, 6-1.

Top-seeded Serbian Jankovic and the rest of the top eight players all received first-round byes.

Jankovic will be playing for the first time since hurting her right knee at Wimbledon, where she limped out in the fourth round with a loss to Tamarine Tanasugarn.

Jankovic, 23, could take over the world number one ranking from compatriot Ana Ivanovic with a victory this week.

But she admitted her knee was still a concern, especially with the Beijing Olympics and US Open — the last Grand Slam of the year — looming.

Fitness is also a question for second-seeded American Williams, who withdrew while trailing from her semifinal match in Stanford, California, on Saturday with a sore left knee.

"I've been playing a lot of tennis," Williams said. "That's basically what it is, a lot of use."

She is scheduled to open on Wednesday against Czech Petra Kvitova - a 6-4, 1-6, 7-5 winner over Russian Alisa Kleybanova on Monday.

"I'm taking it day-by-day," Williams said.

The tournament at the Home Depot Center in the Los Angeles suburb of Carson has already lost several big names to injury, icluding Wimbledon champion Venus Williams, Lindsay Davenport and Kuznetsova.

Austrian Sybille Bammer, seeded 14th, got off to a quick start, winning the first 11 games en route to a 6-0, 6-4 victory over US qualifier Ahsha Rolle.

Rolle finally mustered some resistance, breaking Bammer's serve twice in the second set before the Austrian reasserted herself to win the match.

India's 16th seed Sania Mirza also advanced, defeating Czech qualifier Eva Hrdinova 6-3, 6-4.

AFP