Federer and Serena step up a gear

Top seeds Roger Federer and Serena Williams moved up a gear on Saturday with straight sets wins as they closed in more silverware at the Australian Open.

The world's premier players have 26 Grand Slam titles between them and both look primed to add to their collections.

The Swiss great made short work of Spanish 31st Albert Montanes 6-3, 6-4, 6-4 while Williams completed a 6-0, 6-3 demolition of Carla Suarez Navarro as the fourth round of the opening Grand Slam of the season took shape.

Federer, with 15 Grand Slam titles, now faces a round of 16 clash against either Lleyton Hewitt or Marcos Baghdatis, who play later while Williams will take on 13th seed Australian Samantha Stosur.

"I've come through a difficult draw, I feel physically fine and mentally fresh, but the opponents will get tougher from here," said Federer.

The imposing and super-fit Stosur, blessed with one of the biggest serves in women's tennis, had a breakthrough 2009, making the semi-finals at the French Open and was in top form Saturday.

She outclassed Italy's Alberta Brianti 6-4, 6-1 on Rod Laver Arena and is gunning for another crack at Williams, who she beat when they last met in Stanford in July.

"We've had a couple of close matches the last two times we've played and I got the last one so I'm going to ride with that and go into the match feeling pretty confident," Stosur said.

"I know I'm going to have to play extremely well to try and beat her and I'm going to give it my best shot and hopefully I can do well."

Also pushing into the fourth round were seventh-seeded Belarrussian Victoria Azarenka, who destroyed Italy's Tathiana Garbin 6-0, 6-2.

Russian ninth seed Vera Zvonareva beat Argentine Gisela Dulko, the conqueror of Ana Ivanovic in the previous round, 6-1, 7-5 and will play Azarenka for a place in the quarters.

"I think I did very well today. I had a good game plan and I definitely played to it very well," said Azarenka.

"I was going for my shots and playing comfortably and confident."

Serena's sister Venus has been quietly making her way through the draw and will take on Australian Casey Dellacqua later Saturday, while Chinese hope Li Na is up against off-court friend Daniela Hantuchova.

Russian sixth seed Nikolay Davydenko is in action against Argentina's Juan Monaco, with the winner challenging either ninth seed Fernando Verdasco or qualifier Stefan Koubek for a place in the quarter-finals.

Little-known Pole Lukasz Kubot is already through to the fourth round after being handed a free ride when Russian 20th seed Mikhail Youzhny withdrew with a wrist injury.

Youzhny played one of the matches of the tournament in the first round when he beat Frenchman Richard Gasquet in the fifth set, but said the win took its toll with his wrist beginning to hurt late in that epic.

"The next day it was worse and I didn't think I was going to play (second round match against Jan Hajek)," he said.

"I did everything I could do for the last few days, but it doesn't help."

Youzhny added that he had been advised against playing and was unsure when he would return to the court.

The 86th-ranked Kubot will take on either third seed Novak Djokovic or unseeded Uzbek Denis Istomin for a place in the quarters.