Top-seeded Caroline Wozniacki of Denmark dismantled struggling Vania King of the United States, 6-2, 6-4, to reach the fourth round of the U.S. Open on Saturday.

Caroline Wozniacki of Denmark returns to Vania King of the U.S. during their match at the U.S. Open tennis tournament in New York, September 3, 2011.

World No. 1 Wozniacki, the 2009 runner-up, waltzed past 103rd-ranked California native Vania King in 1 hour, 36 minutes.

The 21-year-old Wozniacki, still seeking her first-ever major championship, leads the WTA with six titles already this year, including a fourth straight New Haven championship last week.

"I won. I think that's the most positive," Wozniacki said. "It's great to be through. You know, I was fighting a lot out there, getting quite a lot of balls back."

King captured doubles titles at the U.S. Open and Wimbledon last year, but has never advanced beyond the third round in singles at a Grand Slam event.

2011 French Open runner-up and 2010 Roland Garros titlist Francesca Schiavone staved off a match point before fighting back to beat South African Chanelle Scheepers 5-7, 7-6 (7-5), 6-3, also advanced into the last 16.

Scheepers, who is now 0-8 lifetime against top-10 players, was up a set and leading 5-4 in the second when the seventh-seeded Schiavone saved a match point to extend the bout.

Up next for Schiavone will be 17th-seeded Anastasia Pavlyuchenkova of Russia, who ousted former world No.1 Jelena Jankovic, seeded 11, 6-4, 6-4.

Tenth-seeded rising German Andrea Petkovic reached the fourth round at the U.S. Open for a second straight year by handling 18th-seeded Italian Roberta Vinci 6-4, 6-0.

The 2011 Australia and French Open quarterfinalist Petkovic will next meet Spaniard Carla Suarez Navarro, who easily defeated her countrywoman Silvia Soler-Espinosa 6-0, 6-4.