World No. 1 Victoria Azarenka, former champion Maria Sharapova, and reigning U.S. Open titlist Samantha Stosur moved into the fourth round, while former French Open champ Li Na suffered a third- round upset at the final Grand Slam event of the year -- the U.S. Open.

The world No. 1 Azarenka made quick work of 28th-seeded Zheng Jie of China, as the Belarus native cruised to a 6-0, 6-1 victory in just under an hour at Arthur Ashe Stadium.

Azarenka, who won the Australian Open this year, will take on Anna Tatishvili in the round of 16 after the Georgian ousted Luxemburg's Many Minella 7-5, 6-0 to secure her spot in the fourth round.

The third-seeded former world No. 1 Sharapova continued her recent run of strong Grand Slam play, as the Russian veteran blew away American Mallory Burdette 6-1, 6-1 in a mere 56 minutes.

"I would have loved to have served a little better in that second set," Sharapova admitted. "I gave her that break. But overall, it was pretty solid."

Sharapova has appeared in three of the last five major finals (1-2), including a French Open title run in June to complete a career Grand Slam.

The 2012 Olympic silver medalist and 2006 U.S. Open champion Sharapova will face fellow Russian Nadia Petrova in the round of 16. Petrova upended 15th- seeded Czech Lucie Safarova 6-4, 7-5.

The fifth-seeded left-handed Czech slugger Petra Kvitova handled France's Pauline Parmentier 6-4, 6-4 on the Grandstand court on a very hot day in New York.

Last year's Wimbledon champion will lock horns with 2007 Wimbledon runner-up Marion Bartoli on Sunday.

The seventh-seeded Stosur defeated 31st-seeded Uzbekistanian-born American Varvara Lepchenko 7-6 (7-5), 6-2 at Ashe Stadium.

The Australian Stosur, who stunned American great Serena Williams in last year's finale in Flushing Meadows, will battle upstart British teenager Laura Robson in the fourth round.

"You know, I have never played Laura before," Stosur said. "She's obviously full of confidence and had two very, very good wins. Definitely can't go into that match slightly. Have to go out there and be on my game and ready to play some good tennis."

The ninth-seeded Li was knocked out by the rising Robson 6-4, 6-7 (5-7), 6-2 at Armstrong Stadium. The 18-year-old Robson beat a former major champion for the second time in two matches, as she ended the singles career of three-time U.S. Open winner Kim Clijsters here on Wednesday.

"I think I was making a lot of mistake in my, how you say, whole match, so of course give a lot of free point for her," Li said.

The talented Robson, the youngest woman in the top 100, is now into the fourth round at a major for the first time in her career, and she's the first British woman to reach the round of 16 in Flushing in 21 years (Jo Durie, 1991).

Also on Day 5 at the USTA Billie Jean King National Tennis Center, an 11th- seeded Bartoli handled fellow Frenchwoman Kristina Mladenovic 6-2, 6-4.

The 2012 women's singles champion in New York will earn at least $1.9 million. Kvitova could take home $2.9 million as the result of receiving a $1 million bonus for winning the U.S. Open Series.