STUTTGART, Germany -- Seeded players Li Na, Angelique Kerber and Petra Kvitova advanced to the quarterfinals of the Porsche Grand Prix on Thursday.
The second-seeded Li swept past qualifier Mirjana Lucic-Baroni 6-1, 6-2, and the third-seeded Kerber defeated Anastasia Pavlyuchenkova 6-0, 6-4. The fifth-seeded Kvitova rallied past 2011 champion Julia Goerges 2-6, 7-6 (4), 6-2. Kvitova is the 2011 Wimbledon champion and looking for her second title of the year.
Ana Ivanovic beat eighth-seeded Nadia Petrova 6-4, 6-3. One day after upsetting Caroline Wozniacki, Carla Suarez Navarro lost 7-5, 6-4 to Yaroslava Shvedova.