By JOHN PYE AP Sports Writer MELBOURNE, Australia (AP) -- Defending champion Kim Clijsters and No. 1-ranked Caroline Wozniacki advanced to the third round of the Australian Open in contrasting styles on Wednesday. Clijsters needed only 47 minutes to beat Stephanie Foretz Gacon of France 6-0, 6-1, then showed just how much support she has at Rod Laver Arena by getting the crowd to sing 'Happy Birthday' to her younger sister. Wozniacki seemed to be on the same trajectory, but had to battle to beat Anna Tatishvili of Georgia in the second set, recovering two service breaks and saving a set point en route to a 6-1, 7-6 (4) win. She needs to reach the quarterfinals to have a chance of retaining the top ranking she held for all but one week in 2011. That's also the stage when she could come across Clijsters. The No. 11-seeded Clijsters showed no signs of a hip problem that forced her to retire during a semifinal against Daniela Hantuchova at a warmup tournament two weeks ago. She will meet Hantuchova in the next round here, and has a potential rematch of the 2011 Australian Open final with French Open champion Li Na in the fourth round. Rafael Nadal and Roger Federer took differing paths against German rivals to the next stage. Nadal beat Tommy Haas 6-4, 6-3, 6-4 in the last afternoon match on Rod Laver Arena. Second-seeded Nadal had his right knee heavily taped again after hurting it while sitting in a hotel chair on the weekend, but it didn't seem to restrict him. "Much better, I am very happy about how the knee is improving," Nadal said. "I am playing without problems, so that's OK." Federer, who has won four of his 16 Grand Slam titles in Australia, got a walkover into the third round when Andreas Beck withdrew from their scheduled Hisense Arena match due to a lower back injury. It deprived Federer of a different view at Melbourne Park, where he has played every match in Rod Laver Arena since the third round of the 2004 Australian Open. Eighth-ranked Mardy Fish became the first top 10 player on the men's side to lose, falling 7-6 (4), 6-3, 7-6 (6) to Colombia's Alejandro Falla. No. 7 Tomas Berdych advanced 6-1, 6-0, 7-6 (4) over Olivier Rochus of Belgium, 2009 US Open champion Juan Martin del Potro, No. 18 Feliciano Lopez and No. 30 Kevin Anderson all advanced. On the women's side, 10th-seeded Francesca Schiavone was eliminated 6-4, 6-3 by fellow Italian Romina Oprandi and No. 16 Peng Shuai lost 6-2, 6-4 to Iveta Benesova of Czech Republic. Former No. 1-ranked Jelena Jankovic beat Chang Kai-chen of Taiwan 6-4, 6-2. Clijsters and No. 20 Hantuchova, a 4-6, 6-4, 6-3 winner over Lesia Tsurenko, have been playing each other for years. "When the injury happened, it happened against Daniela," Clijsters said of the hip muscle spasms she had at the Brisbane International. "She's been playing well this season so far. "We both go back a long way -- we grew up playing under-14s together. Now almost 30 -- still battling it out." This was Clijsters' best run at a major since the last Australian Open -- she lost in the second round at the French Open and didn't play Wimbledon and the US Open. Li is also returning to form, going further than she has at a Grand Slam tournament since her breakthrough win at the French Open. She went out in the second round at Wimbledon and the first at the US Open, but reached the third round at Melbourne Park with a 6-2, 6-2 win over Olivia Rogowska. She next plays No. 26 Anabel Medina Garrigues of Spain, who beat Olga Govortsova of Belarus 6-1, 6-0. Li said she loved being back on Rod Laver Arena, where she burst onto the global tennis scene last year, while Clijsters still clearly feels at home on a court where she's still known as "Aussie Kim" long after her relationship with Lleyton Hewitt ended. In a post-match TV interview, she asked presenter Rennae Stubbs a favour, saying her brother-in-law phoned her from Belgium to ask if she could convince the crowd to sing a birthday song for Elke, Clijsters' younger sister. The crowd obliged, after Clijsters kicked it off. Li took longer for her second-round win, saying it was harder than the scoreline suggested. She also has fond memories of Melbourne Her form dipped after the French Open, with losses in the second round at Wimbledon and the first round at the US Open, until she returned to Australia. Coming off a run to the final at last week's Sydney International, Li was the first woman into the third round. Li, who will be 30 next month and is seeded No. 5 at Melbourne Park, said she had great memories of the start of 2011. "I'm feeling always good to come back to Rod Laver Arena," she said, reflecting on how her life had changed dramatically since last season started. "This year is much better than last year -- more fans come to watch me play, not only from China but all over the world." Serena Williams advanced to the second round in a match that finished after midnight, her ankle holding up to its first test since she sprained it in Brisbane two weeks ago. The only thing that bugged her, despite the 11:32pm start on Tuesday, were the insects in a 6-3, 6-2 win over Tamira Paszek. "I hate bugs more than you can imagine," Williams said. "Like, they kept jumping on me. Yuck!" "I'm going to request not to play at night anymore because I hate bugs, except for the final. I heard it's at night," Williams said. "I'll try to get used to them." She's on a 15-match winning streak at Melbourne Park, having skipped last year after winning back-to-back titles in 2009 and '10. Williams was playing only her third match since losing the US Open final to Sam Stosur last September, so she admitted being "a wee bit tight." Wimbledon champion Petra Kvitova and No. 4-ranked Maria Sharapova also advanced. Stosur didn't make the second round, losing 7-6 (2), 6-3 to No. 59-ranked Sorana Cirstea, but fans hung around to watch another Aussie hope. Hewitt, a two-time major winner, gave the night session crowd something to cheer when he beat Cedrik-Marcel Stebe of Germany 7-5, 6-4, 3-6, 7-5. That put him into a second-round match against old rival Andy Roddick. Defending champion Novak Djokovic and two-time finalist Andy Murray advanced a round closer to a potential semifinal meeting.