Williams sisters roll on in Australia

(GETTY IMAGES)

Serena Williams joined older sister Venus in the third round of the Australian Open today as the main contenders continued to move safely and swiftly through the draw.

Serena had no problems defeating Czech Petra Kvitova 6-2 6-1 to remain on course to defend the title she won last year while Venus cruised to a 6-2 7-5 victory over Austria's Sybille Bammer.

Serbia's Novak Djokovic, the 2008 champion, survived a shaky start to win while in-form Russian Nikolay Davydenko and Australia's Lleyton Hewitt advanced in straight sets.

Denmark's Caroline Wozniacki also sailed through, beating Germany's Julia Goerges 6-3 6-1, but in a tournament bereft of major upsets, there were at least two surprises on Thursday.

The former world number one Ana Ivanovic bowed out after a 6-7 7-5 6-4 loss to unseeded Argentinian Gisela Dulko while Marcos Baghdatis turned back the clock to defeat Spain's David Ferrer, the 17th seed.

Baghdatis has been plagued by injuries since his rollercoaster ride to the 2006 Australian Open final but showed that he is getting back to his best after fighting back to beat Ferrer 4-6 3-6 7-6 6-3 6-1.

"I saw he was a bit tired, so it helped me fight even more," Baghdatis said.

"I saw a window open, so that's how it went.

"Then my tennis came back. I started playing pretty good. I'm delighted I won."

Ivanovic made the final in Australia in 2008 and won the French Open that same year but her career has been in freefall ever since then and she has slipped to 21st in the rankings despite trying desperately to resurrect things.

"It's a process. I think I just have to be patient," she said.

"Some matches it's there, some not. I just have to sort of keep my head up and try to improve."

Djokovic was unusually tentative at the start of his match but was too streetwise for Switzerland's Marco Chiudinelli, winning 3-6 6-1 6-1 6-3.

"I was frustrated, especially at start of the match, because he was really giving it to me. He was very aggressive and stepping in and using ever opportunity that has been given to him," Djokovic said.

"So automatically I just became too defensive and didn't really make too much. Just waiting for his mistakes.

"That was a little issue there but I managed to make that transition from being defensive to being offensive and changing pace and holding the game in control in the second and third set."

Davydenko steam-rolled Ukraine's Illya Marchenko 6-3 6-3 6-0 to maintain his unbeaten start to the year as he chases his maiden grand slam title while Hewitt survived a dogged challenge from American Donald Young to win 7-6 6-4 6-1.

Roger Federer was scheduled to play his second round match on Thursday's night session on the Rod Laver Arena.