U.S. Open champion Samantha Stosur, former Wimbledon runner-up Marion Bartoli and reigning French Open champ Li Na highlighted Tuesday's opening-round winners at the $740,000 Porsche Tennis Grand Prix.

The fifth-seeded 2010 Stuttgart runner-up Stosur leveled Chinese Peng Shuai 6-2, 6-2, while a seventh-seeded Bartoli blitzed Czech lefthander and qualifier Iveta Benesova 6-3, 6-2 on the indoor red clay at Porsche Arena.

Reigning Stuttgart titlist Julia Goerges pleased the home crowd with a 5-7, 6-3, 6-4 victory over Russian Anastasia Pavlyuchenkova. The German Goerges stunned a then-world No. 1 Caroline Wozniacki in last year's final here.

Goerges will tangle with Stosur in her next outing.

The eighth-seeded Li of China defeated Czech Republic's Lucie Safarova 7-6 (7-4), 6-4 in 92 minutes, while former top-10 star Andrea Petkovic played her first tennis in more than three months and made it count Tuesday with a 6-1, 6-4 victory over fellow German Kristina Barrois.

The 12th-ranked Petkovic, who opened the year ranked 10th in the world, was forced to the sidelines in January after suffering a back injury just before the start of the Australian Open.

Petkovic is rewarded with a tough second-round assignment against Australian Open champion Victoria Azarenka, who has lost only once this season.

Rising German Angelique Kerber clobbered Italian Roberta Vinci 6-2, 6-3, while former French Open champ and 2011 Roland Garros runner-up Francesca Schiavone got past Romanian Monica Niculescu 6-3, 7-5 on Tuesday. Schiavone will meet Wimbledon champ Petra Kvitova in the round of 16.

Kerber titled in Copenhagen two weeks ago by stunning the former No. 1 Wozniacki in the final.

Other Day-1 wins came for Hungarian qualifier Greta Arn and French qualifier Alize Cornet, who blew past qualifier and fading former top-five star Anna Chakvetadze of Russia 6-3, 6-4. Cornet is rewarded with a second-round match Wednesday against another Russian, Maria Sharapova, while Arn will face fourth-seeded rising Pole Agnieszka Radwanska on Day 2.

The top seeds at this star-studded event are the world No. 1 Azarenka, the former No. 1 Sharapova, and Kvitova. A sixth-seeded Wozniacki is also part of the field.

The 2012 Stuttgart champion will claim $37,000 and a new Porsche.