Anna Chakvetadze lies prostrate on the court after fainting during her match against Caroline Wozniacki.

STORY HIGHLIGHTS

• Caroline Wozniacki moves to within two wins of reclaiming world number one spot
• Danish star reaches last 16 in Dubai as opponent Anna Chakvetadze faints on court
• Chakvetadze retires after incident and is treated for a stomach upset
• Scot Andy Murray pulls out of next week's ATP event in Dubai through injury

(CNN) -- Caroline Wozniacki moved a win nearer to reclaiming the world number one spot from Kim Clijsters but her passage to the last 16 in Dubai only came after her Russian opponent, Anna Chakvetadze, fainted on court.

Chakvetadze was serving to level their match at one set all when she collapsed and fell to the ground.

Wozniacki and courtside officials all rushed to help Chakvetadze, who eventually came around but played just one more point before wisely retiring.

Wozniacki, who took the first set 6-1 but trailed 3-5 in the second, was shocked by the incident.

"It was scary. She is a good friend of mine, but to see anyone collapse on the other side of the net is not a good sight. It was quite a surprise," she told AFP.

It was scary. She is a good friend of mine, to see anyone collapse on the other side of the net is not a good sight
--Caroline Wozniacki

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Chakvetadze, who put out Pattaya Open winner Daniela Hantuchova in the first round, was later diagnosed with a gastro-intestinal illness.

Wozniacki, who needs to reach the semifinals in Dubai to dislodge Australian Open champion Clijsters, next plays Ayumi Morita as the Japanese qualifier continued her superb run.

Morita beat Clijsters' Paris final conqueror Petra Kvitova in the first round and followed that up Wednesday with a straight sets win over Sania Mirza, the Indian star now based in Dubai.

Morita eased to a 6-4 6-2 win while Russia's Svetlana Kuznetsova earned another meeting with Francesca Schiavone of Italy.

Kuznetsova lost to the French Open winner in the longest women's match in grand slam history in last month's Australian Open, four hours 44 minutes.

Kuznetsova needed two-hours 30 minutes to beat Tavetona Pironkova by 5-7 6-2 6-3 to earn a chance of revenge.

"I think every single person who knows me watch that match in Melbourne came to me and said it was a great match," Kuznetsova said.

Meanwhile, Britain's Andy Murray has withdrawn from next week's ATP tournament in Dubai, citing a wrist injury.

Murray, beaten in the final of the Australian Open by Novak Djokovic, played last week in Rotterdam, but was well below his best and won only five games in losing his first-round clash to Marcos Baghdatis.

His withdrawal will mean the 23-year-old is not due to play again until the Masters Series event in Indian Wells in the middle of next month.

"Andy would like to apologize to both the tournament and its fans," he told his official website.

Roger Federer and Australian Open champion Novak Djokovic are among the entries for the popular tournament.