Sydney - Fifth-seeded Angelique Kerber of Germany beat Dominika Cibulkova of Slovakia 7-6 (5), 7-5 on Monday to move into the second round of the Sydney International, one of the last warm-up tournaments for the Australian Open starting next week.
Kerber will next play Estonia's Kaia Kanepi, who beat American qualifier Victoria Duval 6-1, 6-3.
In other first-round matches, Lucie Safarova beat 2010 French Open champion Francesca Schiavone 6-4, 6-4 and American Bethanie Mattek-Sands had a 6-4, 6-3 win over Canada's Eugenie Bouchard.
Two other U.S. players advanced, with Lauren Davis beating Australia's Jarmila Gajdosova 6-4, 7-6 (8) and Varvara Lepchenko scoring a 6-3, 3-6, 7-5 win over two-time major winner Svetlana Kuznetsova of Russia. Tsvetana Pironkova of Bulgaria beat Sorana Cirstea of Romania 6-4, 6-1.
On the comeback from a long layoff with a knee injury, Mattek-Sands had a first-round loss in Brisbane last week and went through three rounds of qualifying for Sydney. She next faces defending champion and No 1-seeded Agnieszka Radwanska.
"She reads the ball so early so it's going to be a great battle," Mattek-Sands said of her second-round match. "But I'm looking forward to it. This is why you train - it's to play the best players in the world. So why not play the No 1 seed?"
The Hobart International had another injury setback on Monday when fifth-seeded Flavia Pennetta withdrew citing a wrist injury, a day after Venus Williams pulled out following her run to the final at the ASB Classic in Auckland, New Zealand.
In first-round Hobart matches, Spanish qualifier Estrella Cabeza Candela beat Karin Knapp of Italy 7-5, 6-4, Australian wildcard entry Casey Dellacqua beat Belgian qualifier Alison Van Uytvanck 6-4, 6-4 and Zhang Shuai had a 6-3, 6-1 win in an all-Chinese match against Zheng Jie.