SYDNEY, Australia -- U.S. open champion Kim Clijsters was an easy second-round winner, while world No. 1 Caroline Wozniacki was upended by scrappy Slovak Dominika Cibulkova at the Sydney International tennis event, a final Australian Open tuneup.
The third-seeded former No. 1 Clijsters handled Czech qualifier Barbora Zahlavova Strycova 6-1, 6-4, while Wozniacki gave way to Cibulkova 6-3, 6-3. It marked Cibulkova's first-ever victory against a top-ranked player. She'd lost her last five matches against Wozniacki.
The three-time U.S. Open champion and former Aussie Open runner-up Clijsters is a two-time Sydney titlist (2003, 2007).
The upset bug also bit second-seeded Russian Vera Zvonareva and fourth- seeded Aussie crowd favorite Samantha Stosur. The 2010 Wimbledon and U.S. Open runner-up Zvonareva was upended by Italian Flavia Pennetta 7-5, 7-5, while Stosur lost to former top-five Russian star Svetlana Kuznetsova 3-6, 6-3, 6-4.
Seventh-seeded Belarusian Victoria Azarenka defeated Israel's Shahar Peer 7-5, 6-3, while No. 8 seed Li Na of China outlasted French qualifier Virginie Razzano 6-4, 1-6, 6-4.
Additionally, Alisa Kleybanova of Russia advanced with a 6-2, 6-4 victory over Spain's Maria Jose Martinez Sanchez and Serbian qualifier Bojana Jovanovski snuck past France's Aravane Rezai 7-6 (7-4), 7-6 (7-4).
Wednesday's quarterfinals will pit Clijsters against Azarenka; Li versus Kuznetsova; Jovanovski against Pennetta; and Cibulkova versus Kleybanova.
