Top seeds untroubled at Australian Open

Normal service resumed at the Australian Open on Saturday as Roger Federer and Serena Williams booked their places in the second week of the championship.

Nadia Petrova had given hope to the would-be giantkillers still left in the tournament when she upset Kim Clijsters on Friday but everything went according to the script in Saturday's third round clashes.

Federer, his confidence growing with each match, provided a masterful display against Spain's Albert Montanes, winning 6-3, 6-4, 6-4 to extend his incredible record of making it to the last 16 of every grand slam since the 2004 French Open.

"I don't want to say I'm playing the best tennis of my life, because I haven't had to so far," the world number one said.

"I'm happy I survived a scare against Andreev. After that, I was able to come through comfortably in the next two rounds into week two.

"I feel like I'm obviously fresh and ready to take on the bigger names."

Williams also turned in her best performance of the week, trouncing Spain's Carla Suarez Navarro 6-0, 6-3 to remain on track to defend the title she won the fourth time last year.

"I felt like I played okay," Williams said. "I still feel like I can do better."

Her older sister Venus had a tougher time but still managed to carve out a 6-1, 7-6 win over Australia's Casey Dellacqua and said she had lost none of her hunger.

"Who's ever satisfied? The people that have retired," she said. "The people still on tour, we're not satisfied. I think that's definitely my attitude."

Serbia's Novak Djokovic showed that he was building the kind of momentum that carried him to the 2008 title, giving up just four games in a 6-1, 6-1, 6-2 demolition of Uzbekistan's Denis Istomin.

"At some stage in the tournament you want to have a straight sets win, an easy win, so you can get fast off the court and try to save all the energy as much as you can for the upcoming challenges, which are obviously gonna be more difficult," Djokovic said.

"So it was good to have the match like this."

Nikolay Davydenko is also continuing to impress those who tipped the Russian as a dark horse for the title after he eased to a routine 6-0, 6-3, 6-4 victory over Spain's Juan Monaco.

Yet to drop a set this week, Davydenko will play Fernando Verdasco in the fourth round after the Spaniard was gifted a place in the last 16 when his exhausted Austrian opponent Stefan Koubek retired from the effects of a mystery virus.

Poland's Lukasz Kubot was also given a free ride into the next stage against Djokovic when a wrist injury forced Russia's Mikhail Youzhny to withdraw from their match.

Federer made a shaky start in his opening round match against Russian Igor Andreev but has gradually improved with each match. He plays either Lleyton Hewitt or Marcos Baghdatis next.