Andrea Petkovic went dancing into the sweet 16 on Saturday afternoon at the US Open. And no, it's not March.

The 10th-seeded German started slowly against No. 18 seed Roberta Vinci before breaking away from the tricky Italian and never looking back, winning the match 6-4, 6-0 on Grandstand in one hour and seven minutes.

The 23-year-old, known by diehard tennis fans for her "Petko-dance," an after-match celebratory jig that is ever-changing, trotted on court to do her current version (likened to the worm, if you must know) and even got TV commentator and former Wimbledon finalist Mal Washington to dance a bit with her after an on-court interview.

"She plays differently with the slice, so I just tried to mix it up," Petkovic said of Vinci after her win. "The experience from last year really helped. I struggled with my nerves and my mental toughness. With the experience I much more calm."

Petkovic is referring to her 2010 trip to the US Open, when she advanced to the fourth round only to be soundly beaten by Vera Zvonareva at Arthur Ashe Stadium.

On Grandstand Saturday afternoon there were no visable nerves for the world's no. 11 player. She dictated points with her big baseline game, smacking forehands to counter Vinci's slice backhand. After failing to serve out the set at 5-3, Petkovic rifled a forehand return winner to grab the first point of the tenth game and then finished off the set when Vinci netted a forehand herself.

In the second set, Petkovic had it easy with the 28-year-old Italian. At times her play looked effortless, hitting a drop shot early in the second game of the set to break Vinci. She closed out the match by breaking Vinci for the sixth time in 14 tries.

Petkovic joins Germans Sabine Lisicki and Angelique Kerber in the fourth round, marking the first time that three women from Germany have advanced to the fourth round at the US Open since 1987, when Steffi Graf was runner-up here.

Vinci has made the third round at three straight majors this year. She has been having a banner year, winning three titles and bringing in a 36-22 record into today's match. She scored major upsets in Toronto this summer, knocking out world no. 1 Caroline Wozniacki and Ana Ivanovic en route to a quarterfinal finish. That result brought her inside the top 20 for the first time in her 13-year career.

If 2011 has been a good year for Vinci, it has been a great one for the 23-year-old Petkovic. The German found her way to the quarterfinals at both the Australian and French Opens, while also recording wins over Wozniacki, Venus Williams, Maria Sharapova and Jelena Jankovic. She won a title in Strasbourg, France, earlier this year and made appearances in the semifinals at big events in Miami and Toronto.

Petkovic will next face 79th-ranked Carla Suarez Navarro. While the German hasn't lost to a player outside the top 20 since Wimbledon, Suarez Navarro, a Spaniard, owns a 1-0 record against Petkovic, beating her in straight sets at last year's Australian Open.

• Roberta Vinci Bio
• Andrea Petkovic Bio