DUBAI, United Arab Emirates - Top seeds Caroline Wozniacki and Vera Zvonareva reached the third round at the $2.05 million Dubai Tennis Championships.
The top-seeded former world No. 1 Wozniacki was leading former top-10 Russian Anna Chakvetadze 6-1, 3-5 when Chakvetadze collapsed on the court and was forced to retire from the match.
Chakvetadze was serving for the second set when she fainted during the third point of the ninth game of the stanza. She received extensive medical treatment and then returned for one more point before quitting and tearfully hugging Wozniacki.
The 23-year-old Chakvetadze was suffering with a stomach illness on the hardcourts at Dubai Tennis Stadium.
Wozniacki was supplanted atop the women's rankings by Australian and U.S. Open champion Kim Clijsters on Monday, but the Dane can reach No. 1 again this week if she can reach the semifinals.
The Danish Wozniacki's third-round opponent on Thursday will be Japan's Ayumi Morita.
A second-seeded Zvonareva, meanwhile, leveled Italian Roberta Vinci 6-3, 6-1 to set-up a third-rounder against 15th-seeded fellow Russian Alisa Kleybanova, who handled Aussie Jarmila Groth 6-4, 6-3 on Day 3.
Third-seeded French Open champion Francesca Schiavone of Italy whipped Chinese Zhang Shuai 6-3, 6-1, while fourth-seeded French Open runner-up Samantha Stosur of Australia pasted last week's Pattaya City runner-up Sara Errani of Italy 6-0, 6-1, and Belgian Yanina Wickmayer upended fifth-seeded Aussie Open runner-up Li Na of China 6-7 (6-8), 7-6 (8-6), 6-2. Schiavone will next face former top-five star Svetlana Kuznetsova in a rematch of their longest-ever women's Open Era Grand Slam match last month at the Aussie Open, where the Italian beat the Russian in a 4-hour, 44-minute fourth-round epic.
Sixth-seeded former No. 1 Jelena Jankovic of Serbia subdued South African Chanelle Scheepers 6-2, 6-3; seventh-seeded 2010 Dubai runner-up Victoria Azarenka overcame Chinese Peng Shuai 4-6, 6-2, 7-6 (7-5); eighth-seeded Pole Agnieszka Radwanska rolled past Latvian Anastasija Sevastova 7-5, 6-4; ninth- seeded Israeli Shahar Peer topped Romanian Alexandra Dulgheru; and 10th-seeded former Wimbledon runner-up Marion Bartoli of France foiled Swiss Timea Bacsinszky 3-6, 6-4, 6-1. The Belarusian Azarenka lost to American Venus Williams in last year's finale here.
Other seeded second-round winners were No. 11 Italian Flavia Pennetta, No. 12 Estonian Kaia Kanepi and the No. 16 Kuznetsova, who came from behind to best 2010 Wimbledon semifinalist Tsvetana Pironkova of Bulgaria 5-7, 6-2, 6-4. Kuznetsova was the Dubai runner-up in 2004 and 2008.
Additional second-round wins came for the aforementioned Morita and Swiss veteran Patty Schnyder.
The 2011 Dubai titlist will collect $360,000.