Maria Sharapova, Petra Kvitova, Ekaterina Makarova, Ana Ivanovic, Sara Errani and Zheng Jie have all moved into the fourth round of the Australian Open.
Former champion Sharapova beat German Angelique Kerber in straight sets while Kvitova's Russian opponent Maria Kirilenko retired with a leg injury.
Seventh seed Vera Zvonareva fell in straight sets (7-6 [7)] 6-1) to compatriot Makarova while Ivanovic made short work of Vania King, bundling her out 6-3, 6-4.
Italian Errani took longer to beat Romania's Sorana Cirstea 6-7(6), 6-0, 6-2 and China's Zheng Jie upset ninth seed Marion Bartoli.
Zheng, a semi-finalist in Melbourne in 2010, beat Bartoli 6-3, 6-3 to set up a fourth round clash against Errani.
Second seed Kvitova was handed a berth when Kirilenko retired with the thigh injury while trailing 6-0, 1-0.
The Czech said she had to convince herself to keep playing at a high level as Kirilenko, who was hurt in the first game, put up little resistance.
"I just said to myself that I have to play still the same way as before and go for the balls and don't make many mistakes and by focused," Kvitova said.
Kvitova buried her head in a towel as she waited while Kirilenko went off court for an injury spell.
"Sometimes a timeout is very tough for us because when you are playing really well and then you have five minutes off, sometimes it's tough to get back and play as before," she said.
Kirilenko, the number 27 seed, said she had strained her abductor muscle, a problem she also suffered three years ago.
"I started to feel it in the first game," she said. "The game was very long but it was not so bad so I could still run.
"Then suddenly at 4-0 I was serving and I did a serve-volley and then I felt it badly.
"When I went back to the baseline and couldn't walk properly so I asked for the trainer."
Kirilenko said she took three weeks to recover the first time she had the injury and hopes that with rest, she will be fit to resume playing soon.
Sharapova won 6-1, 6-2, a scoreline that flattered the fourth seed, who was pushed hard by Kerber in the second set before winning in just under an hour-and-a-half.
The Russian, who won in Melbourne in 2008, broke Kerber three times in each set but had to battle in the second set as the German 30th seed lifted her game.
"I played a really good first set but she certainly stepped up in the second," Sharapova said.
"She was a semi-finalist at the US Open (in 2011) so she has been on the big stage before and I knew she could produce some good tennis.
"The second set was a lot tougher than the scoreline suggests."
Sharapova did not help her cause with 22 unforced errors, 15 of those coming in the second set.
But she always looked in control against Kerber, who defended well but was rarely able to come up with a big shot to hurt the Russian.
Sharapova remains in contention to finish the Australian Open with the world number one ranking, along with current holder Caroline Wozniacki, Petra Kvitova and Victoria Azarenka, all of whom are into the fourth round.
AAP/AFPTags: australian-open, tennis, sport, melbourne-3000, vic, australia First posted January 21, 2012 12:01:40