Murray had the simplest of tasks against a weakened Gilles Simon, still struggling after his marathon win over Gael Monfils, while Federer easily had the weapons to deal with the machine-gun serve of Milos Raonic.

Federer, playing in the showpiece evening match on Rod Laver Arena, needed a solitary break to edge the first set, and then won tiebreaker for the second before he swept through the last to take it 6-4, 7-6 (7/4), 6-2.

The Swiss master, now into his 35th consecutive Grand Slam quarter-final and seeking his 18th major title, said "good reflexes" were the key to coping with Raonic's bullet serve.

"You try to anticipate a bit, and it happened better and better as the match went on," he said.

"It's important to stay focused. I have learned that over the years, and it pays off in the end."

While defending champion Djokovic battled to recover from his five-hour, five-set win which concluded in the early hours of Monday, Simon was still struggling from his marathon victory over Gael Monfils a day earlier.

The Frenchman, who could hardly walk after wrapping up the five-setter post-midnight, was in no state to face US Open champion Murray, and he quickly went down 6-3, 6-1, 6-3, calling it "a painful hour-and-a-half."

Murray called it a "tough situation" but he admitted his mind was already on his next match, a quarter-final with France's world number 36 Jeremy Chardy.

The Briton will face Federer in the semi-finals if the pair win their respective quarter-final matches.

Chardy, who comes from the same coaching stable as Williams, reached his first Grand Slam quarter-final with a straight-sets defeat of Italian Andreas Seppi.

He had never previously gone past the second round in Melbourne.

Jo-Wilfried Tsonga, buoyed by new coach Roger Rasheed, beat Richard Gasquet in four sets to tee up a quarter-final against Federer.

Meanwhile the women's competition hotted up as Williams ran over a stunned Maria Kirilenko 6-2, 6-0 and her potential semi-final opponent, title-holder Victoria Azarenka, dominated Elena Vesnina 6-1, 6-1.

Williams dispatched Kirilenko in less than an hour as she reached her 35th Grand Slam quarter-final and set up a last-eight clash with fellow American Sloane Stephens, 19, who beat Serbia's Bojana Jovanovski.

"I haven't beaten Serena and I hope I'll give you all a good show," said the confident teenager.