The Swiss defending champion and second seed took 2hr 25min to wear down the unseeded Spaniard Tommy Robredo 6-3, 3-6, 6-2, 6-2.

The last time the Swiss great missed out on a Slam quarter-final was at the 2004 French Open when he was knocked out by Gustavo Kuerten in the third round.

Federer, who is on a 14-match winning run, will play either four-time semi-finalist Andy Roddick of the United States or compatriot Stanislas Wawrinka in Tuesday's quarters.

"I'm in another quarter-final and I've got all the chances to make it to the semis again, so I'm very pleased," he said.

"It's been a tough first week with a bit of heat in the last couple of matches I played in.

"I'm pretty happy how I'm hitting the ball and I've had a tricky draw with guys with experience or great return players."

Federer said the Australian Open was far from a closed shop between world number one Rafael Nadal and him.

"I think Andy (Roddick) and Novak (Djokovic) are playing extremely well, and that's why I'm not really looking very far ahead here," he said.

"I really think the top seeds here again are showing that they're above the rest a bit at the moment still. Interesting second week, I think."

Federer got away to a solid start but began mistiming his shots and lost rhythm to drop the second set before re-establishing command and pulling away from Robredo in the final two sets on Rod Laver Arena.

"Tommy makes you work extremely hard, he has a great forehand and I'm sweating bullets and happy the match is over," Federer said soon after coming off court.

"I was struggling with my returns in the second set and lost rhythm from the baseline and the game when I was 4-3 down was not my best.

"I came out for the third set looking to try something different as he was doing a great job in moving me around and I played a huge game to go 2-0."

It was Federer's 10th win is as many encounters against Robredo, against whom he has only dropped three sets. Sunday's victory took him to a record 58 match victories at the Australian Open.

He broke Swede Edberg's record of 56 for most Open Era wins at the Australian Open in the third round against Xavier Malisse.

Federer is bidding for his fifth Australian title and to extend his record Grand Slam haul to 17.

Federer has a winning record against both his potential quarter-final opponents. He leads eighth seed Roddick 20-2 and close friend and number 19 seed Wawrinka 6-1.

If Federer plays Wawrinka in the quarter-finals this week, it will be the first all-Swiss last eight match at a Grand Slam in the Open Era.

It would also be the latest stage of a Grand Slam that two Swiss players have met after Federer defeated Wawrinka in the fourth round at last year's French Open.