California - Ana Ivanovic dominated the second set to beat Sabine Lisicki on Tuesday and advance to the second round of the Bank of the West Classic, while defending champion Dominika Cibulkova made a first-round exit.
The fifth-seeded Ivanovic won 7-6 (2), 6-1 against Lisicki, partially avenging her loss to the German in the previous meeting at Wimbledon.
Experienced duo Venus Williams and Daniela Hantuchova also had first-round wins, while Cibulkova was beaten 6-2, 4-6, 6-2 by Spain's Garbine Muguruza.
Ivanovic took full advantage of Lisicki's weak second serve, winning 16 of 23 points, and though she had 10 break points against her, the Serb saved eight of them, while Lisicki was broken four times from just five opportunities.
"Sometimes just a few points make a difference and it helps to be positive in a tight situation," Ivanovic said. "I did that today in the tiebreak."
Ivanovic is playing her first tournament since hiring Dejan Petrovic as coach, replacing Nemanja Kontic.
"It was a lot of things on and off the court," Ivanovic said of her split with Kontic following the loss to Lisicki at Wimbledon. "He helped me a lot and sometimes these decisions are very hard."
The Serbian next faces qualifier Carol Zhao, who was leading Yanina Wickmayer, 6-2, 1-0, when the Belgian retired because of the effects of a viral infection.
Muguruza played pressure-free tennis to down sixth-seeded Cibulkova, 6-2, 4-6, 6-2, with the tall Spaniard using her strong serve to good effect, winning 71 percent of points on first serve.
"When I play someone higher in the rankings I don't feel pressure," said the 28th-ranked Muguruza. "I just out and play. This is a really fast court and that's good for my game. The court helps me sometimes."
Williams beat qualifier Paula Kania, 6-3, 6-2. She'll next play fourth seeded Victoria Azarenka, whom she has beaten in three previous meetings.
"She's always a tough competitor," Williams said. "I'll need to be focused and on my toes."
Hantuchova downed Argentina's Paula Ormachea 6-3, 6-4 and will face Muguruza in the next round.