MELBOURNE, Australia - Defending champion Victoria Azarenka struggled to hold off injured American Jamie Hampton 6-4, 4-6, 6-2 on Saturday before advancing to the fourth round of the Australian Open.
Hampton, who needed a medical timeout for a lower back problem before she served out the second set and winced in pain, frequently on the verge of tears, throughout the third, still managed to hit 41 winners to keep the top-ranked Azarenka under pressure.
Azarenka appeared frustrated at times, but overcame an early break and fended off triple break point in the seventh game of the deciding set before clinching the match in 2 hours, 9 minutes.
Russia's Maria Sharapova celebrates after defeating Venus Williams Friday.
She didn't help herself with six double faults and 28 unforced errors, but was often pushed to the limit by a rival who was swinging hard at every opportunity.
"She played incredible, went for every single shot. I felt it was touching every single line," Azarenka said. "She took a medical timeout but she rips winners all over the place."
After wasting two set points on Azarenka's serve late in the second set, Hampton had to leave the court for nine minutes to have treatment on her back.
Even with the pain of two herniated disks, the 23-year-old Hampton, from Auburn, Ala., went down swinging - making 47 unforced errors to go with the winners that caught Azarenka off guard and had her asking, loudly at one point, what she could do to counter them.
Azarenka's potential semifinal rival, Serena Williams, had the next match on Rod Laver Arena against Ayumi Morita of Japan. Williams is on a roll, having won the past two majors and warming up for the Australian Open with a title earlier in the month at the Brisbane International.
No. 14 Maria Kirilenko of Russia beat No. 20-Yanina Wickmayer 7-6 (4), 6-3 and awaits the winner of the Williams-Morita match in the fourth round.
Elsewhere, two-time major winner Svetlana Kuznetsova advanced with a 6-2, 4-6, 6-3 win over Spain's Carla Suarez.
On Friday night, Maria Sharapova celebrated with extra exuberance after her 6-1, 6-3 win over Venus Williams, her first victory over the seven-time major winner in a Grand Slam.
"I was just really pumped," she said. "Why shouldn't I be?"
After back-to-back 6-0, 6-0 wins in the first two rounds - the first time that happened at major since 1985 - Sharapova has conceded the fewest number of games en route to the fourth round at the Australian Open since Steffi Graf did so 24 years ago.
Top-ranked Novak Djokovic took another step closer to a third consecutive Australian title, defeating Radek Stepanek 6-4, 6-3, 7-5 in the third round.
Djokovic did not have an easy time against the 31st-seeded Stepanek and was troubled at times by the Czech's serve-and-volley game. But Djokovic came out laughing, and he embraced his opponent over the net at the end.
Djokovic will play Sunday against No. 15 Stanislas Wawrinka, who knocked out the last American man in the draw with a 7-6 (6), 7-5, 6-4 win over No. 20 Sam Querrey. For the second straight year, there will be no American men in the fourth round at Melbourne Park.
Fourth-seeded David Ferrer finished off a 6-4, 6-2, 6-3 win over 2006 Australian finalist Marcos Baghdatis with an ace, advancing to a fourth-round match against Japan's Kei Nishikori.
No. 5 Tomas Berdych beat Austria's Jurgen Melzer 6-3, 6-2, 6-2 and will next play South Africa's Kevin Anderson, who beat No. 22 Fernando Verdasco 4-6, 6-3, 4-6, 7-6 (4), 6-2. Djokovic's Serbian Davis Cup teammate Janko Tipsarevic advanced to a meeting with No. 10 Nicolas Almagro.
In an all-Serbian match of two former No. 1 women, 2008 French Open champion Ana Ivanovic beat Jelena Jankovic 7-5, 6-3. She moved into the fourth round against Poland's Angieszka Radwanska, who is seeded No. 4 and won her 12th straight match - including titles at Auckland and Sydney - with a 6-3, 6-1 defeat of Britain's Heather Watson.