SYDNEY -- Top-ranked Caroline Wozniacki came back from 4-0 down in the final set to beat Dominika Cibulkova of Slovakia 7-5, 2-6, 6-4 Tuesday and advance to the quarterfinals at the Sydney International.
The match ended on a line call that was ruled in and later, on video review, shown to be out by a few millimeters, giving Wozniacki victory on her second match point.
Wozniacki, who was No. 1 for all but one week of last year, has achieved the top ranking without having won a Grand Slam. The Danish player's best finish in four appearances at the Australian Open, which begins next Monday, was the semifinals last year.
"I thought I had lost the match," Wozniacki said of her big third-set deficit Tuesday. "I decided to play free, not care about the score anymore, and it worked out. I hate losing."
Wimbledon champion Petra Kvitova, ranked No. 2 and in position to overtake Wozniacki for the top spot with a win at Sydney, also struggled against an unseeded opponent before advancing to the quarterfinals with a 7-5, 3-6, 6-4 win over Alexandre Dulgheru of Romania.
Kvitova used a strong serve to set up an easy crosscourt forehand at the net to the open corner for the win on her first match point.
"I lost against her (Dulgheru) in the U.S. Open, so it was a little bit in my head, and I wanted to win," Kvitova said.
In other second-round matches, third-seeded Victoria Azarenka of Belarus beat Jelena Jankovic of Serbia 6-4, 6-2, French Open champion Li Na beat Channelle Scheepers of South Africa 2-6, 6-4, 6-1, and seventh-seeded Agnieszka Radwanska of Poland defeated Andrea Petkovic of Germany 7-5, 6-4.
Daniela Hantuchova of Slovakia, beaten by Kaia Kanepi of Estonia in the Brisbane International final last Saturday, defeated 2010 French Open champion Francesca Schiavone of Italy 7-5, 6-1. On Monday, Schiavone beat U.S. Open winner Samantha Stosur of Australia in the first round.