Caroline Wozniacki moved within one victory of regaining the No. 1 ranking after beating Japan's Ayumi Morita 6-1, 6-0 to reach the quarterfinals of the Dubai Championships on Thursday.
The 20-year-old Dane, who lost the top spot to Kim Clijsters on Monday, was never seriously challenged by the 57th-ranked Japanese qualifier. She now must beat Shahar Peer of Israel to return to No. 1. Wozniacki lost to Peer in the third round last year.
In earlier matches, U.S. Open finalist Vera Zvonareva and French Open champion Francesca Schiavone were both eliminated in the third round.
Alisa Kleybanova beat Russian teammate Zvonareva 6-3, 6-2, while Svetlana Kuznetsova defeated Schiavone 1-6, 6-0, 7-5.
Samantha Stosur of Australia also reached the quarterfinals, beating Swiss veteran Patty Schnyder 6-3, 6-4, while Agnieszka Radwanska of Poland defeated Marion Bartoli of France 6-3, 6-2 and Peer overcame a sluggish start to beat Yanina Wickmayer of Belgium 3-6, 6-4, 6-1.
Italy's Flavia Pennetta came back from 4-1 down in the third set to beat seventh-seeded Victoria Azarenka of Belarus 6-3, 6-7 (2), 6-4. Pennetta seemed on her way to a relatively straightforward victory but she blew a 5-1 lead in the second to allow the ninth-ranked Azarenka to level the match.
The highly anticipated match between Schiavone and Kuznetsova lacked the drama of their Australian Open encounter in Melbourne which lasted nearly five hours and was the longest women's Grand Slam singles match in the Open era. Schiavone won that fourth-round match.
After two quick sets that went opposite ways, Kuznetsova needed seven match points to win.
"I said to myself, 'Look, you still have it. You're good enough. It's just matter of closing the deal,'" Kuznetsova said. "I just cannot close it. It's just one point, a stupid point, but it's only one. I win like 101 during the match, and I can't win just final one. It's funny."
Kleybanova had six aces against Zvonareva, an Australian Open semifinalist and runner-up at the U.S. Open and Wimbledon.
"Maybe the score looked easy, but the match wasn't really easy today. We had a lot of fighting in many games," said Kleybanova, who has beaten Zvonareva twice before, the last time in 2009 in Tokyo.
Zvonareva, who reached the quarterfinals last year in Dubai, called the match one of her worst recent performances.
"Definitely, it wasn't my day today. I think I didn't play too good," she said. "Too many unforced errors. Probably one of the worst matches in a while from my part."
Stosur, a 2010 French Open finalist who has started slowly this year, hasn't really been tested yet in Dubai. She only dropped a game in her second round match victory over Sara Errani. Against the 32-year-old Schnyder, Stosur won the first set easily even though she only got 36 percent of her first serves in.
In the second set, Stosur let slip an early break of serve but two double faults from Schnyder helped the Australian player break again for a 5-4 lead before she served out the win with a love game.