Linz, Austria (SportsNetwork.com) - Top seed Angelique Kerber and American Sloane Stephens highlighted Thursday's second-round winners at the Generali Ladies Linz tennis tournament.

The sturdy German left-hander Kerber dismantled Romanian Alexandra Cadantu 6-1, 6-0 in a mere 50 minutes, while the second-seeded 20-year-old Stephens went the distance to stave off former top-10 star Andrea Petkovic of Germany 7-6 (7-1), 4-6, 6-3 in 2 hours, 31 minutes on the indoor hardcourts at TipsArena Linz.

Up next for the recent Tokyo runner-up Kerber will be Austrian crowd favorite Patricia Mayr-Achleitner, while Stephens' quarterfinal opponent on Friday will be Swiss Stefanie Voegele.

Another seed in action on Day 4 was No. 7 and 2011 Linz runner-up Dominika Cibulkova, who drubbed Polish qualifier Katarzyna Piter 6-0, 6-1 in a brisk 52 minutes.

Meanwhile, the wild card Mayr-Achleitner snuck past Ukrainian lucky loser Maryna Zanevska 6-1, 6-7 (1-7), 6-4 and the aforementioned Voegele fought back to beat Italian Karin Knapp 4-6, 6-2, 7-5.

Friday's other quarters will pit third-seeded former world No. 1 Ana Ivanovic against Cibulkova and fourth-seeded Spaniard Carla Suarez Navarro versus fifth-seeded Wimbledon semifinalist Kirsten Flipkens of Belgium. Ivanovic was the Linz titlist in 2008 and 2010.

This week's winner will claim $43,700.