Serena Williams sneaks through in Australian Open

SERENA Williams has struggled her way into the fourth round of the Australian Open with an unconvincing victory over China's Peng Shuai.

The second seed, who laboured through to the third round courtesy of a 6-3, 7-5 win over Argentina's Gisela Dulko, was again far from her best against her unseeded opponent, 6-1, 6-4.

Shuai broke Williams' service on two occasions in the second set but the three-time champion bounced back to ensure a last 16 meeting with Belarus' Victoria Azarenka.

Azarenka, seeded 13th, overcame former champion Amelie Mauresmo 6-4, 6-2.

"She started to play extremely well and get a lot of balls back so in that sense it was a really good match for me to play," said Williams.

"I'm feeling a little rusty, for whatever reason. I'm hoping my next round I'll be a little better."

Elsewhere, fourth seed Elena Dementieva continued her career-best outing at the Australian Open, overcoming Australia's Samantha Stosur 7-6, 6-4.

And unseeded Spaniard Carla Suarez Navarro, having conquered sixth seed Venus Williams, has secured a fourth-round place by defeating compatriot Maria Jose Martinez Sanchez.

Navarro will now square off against fellow Spaniard Anabel Medina Garrigues who came through in straight sets against Italy's Flavia Pennetta while Dementieva meets Slovakia's Dominika Cibulkova.