Melbourne: Seventh-seeded Vera Zvonareva, a two-time semifinalist at Melbourne Park, had a 6-1, 7-6 (3) win over Lucie Hradecka while No. 21 Ana Ivanovic also advanced, beating Dutch player Michaella Krajicek 6-2, 6-3.
Defending champion Kim Clijsters is into the third round on the other half of the draw.
Top-ranked Caroline Wozniacki is aiming for her first major tile, and is one of four women in the draw who can finish the tournament at No. 1.
After her 6-1, 7-6 (4) second-round win over Anna Tatishvili on Wednesday, she asked how her boyfriend might be able to help.
She smiled, paused, then relayed some of the advice Rory McIlroy offered that helped him overcome similar pressure and win a golf major.
"Well, it`s just about you can`t really do anything about the past," Wozniacki said. "You just need to look forward. You have a tournament now, and you want to do the best you can. That`s it.”
"Then if it goes well, it`s great. If not, you have the next one. It`s like tennis."
Wozniacki is into a third-round match against No. 31 Monica Niculescu. A win could put her on course for a quarterfinal match against Clijsters, who routed Stephanie Foretz Gacon of France 6-0, 6-1.
Clijsters will face longtime friend Daniela Hantuchova in the third round, and a win there could set up a fourth-round match against French Open champion Li Na, a rematch of the 2011 Australian final.
Third-seeded Victoria Azarenka advanced in a night match with a 6-1, 6-0 win over Australian wild card Casey Dellacqua. Former top-ranked player Jelena Jankovic stayed alive in the draw after beating Chang Kai-chen 6-4, 6-2 and could be a fourth-round rival for Wozniacki.
On the men`s side, No. 2 Rafael Nadal advanced without much trouble from his injured right knee or from German veteran Tommy Haas in a 6-4, 6-3, 6-4 win. Four-time champion Roger Federer didn`t even need to pick up a racket because Andreas Beck withdrew from their second-round match.
The top-ranked American man bowed out when No. 8 Mardy Fish lost to Alejandro Falla of Colombia 7-6 (4), 6-3, 7-6 (6). But No. 16 John Isner survived a five-setter to beat former Wimbledon finalist David Nalbandian, who was enraged by an umpire who didn`t allow him to challenge a disputed line call because he took too long to ask for a review.
No. 7 Tomas Berdych, 2009 U.S. Open champion Juan Martin del Potro and No. 18 Feliciano Lopez all advanced.
Andy Roddick was scheduled to play the last match Thursday against Lleyton Hewitt in a battle between two former No. 1-ranked players. Defending champion Novak Djokovic has an earlier center court match against Santiago Giraldo. Andy Murray, who has lost the last two Australian Open finals, takes on Edourd Roger-Vasselin.