Melbourne - British third seed Andy Murray capitalised on the weakened condition of an ailing Gilles Simon as he marched into the quarter-finals of the Australian Open on Monday.

The US Open champion was too physical for the French 14th seed, still struggling after a marathon match over the weekend, as he won 6-3, 6-1, 6-3 in 1hr 35min on Hisense Arena.

Murray, twice a runner-up in Melbourne and a semi-finalist last year, will take on another Frenchman, Jeremy Chardy, in the last eight on Wednesday.

Simon was barely mobile around the court following Saturday's nearly five-hour win over fellow Frenchman Gael Monfils, and he was a spent force late in the match.

Murray broke Simon's serve eight times and hit 32 winners with just 26 unforced errors, while the Frenchman could hardly break into a run inside the final set.

"I have to try and focus on my side of the court. He's one of the best movers on the tour and he was clearly struggling in his movement on Monday," Murray said.

"It was tough, but that's what Grand Slam tennis is. The games are so physical nowadays and it was 8-6 in the fifth set the other day and nearly five hours, so it was tough for him."

Murray largely did as he pleased, breaking Simon three times in the opening set, another three times in the second and two more in the final set.

Murray's 10th victory over Simon, whose only win over the Scot was back in 2007 in Rome, took him into his ninth consecutive Grand Slam quarter-final and his 15th overall.

Murray has now won 11 consecutive matches at the majors including his breakthrough US Open triumph in New York last September, when he beat world number one Noval Djokovic in the final.

He now faces up to the 36th-ranked Chardy in the last eight, following the Frenchman's four-set win over Italian 21st seed Andreas Seppi earlier on Hisense Arena.

"Chardy's had two very good wins, he beat Juan Martin Del Potro a couple of rounds ago and I lost to him the last time I played him in Cincinnati, so it will be a tough match," he said.

Results from day eight of the Australian Open on Monday:

Women's singles

Fourth round

Svetlana Kuznetsova (RUS) bt Caroline Wozniacki (DEN x10) 6-2, 2-6, 7-5
Victoria Azarenka (BLR x1) bt Elena Vesnina (RUS) 6-1, 6-1
Sloane Stephens (USA x29) bt Bojana Jovanovski (SRB) 6-1, 3-6, 7-5
Serena Williams (USA x3) bt Maria Kirilenko (RUS x14) 6-2, 6-0

Men's singles

Fourth round

Jeremy Chardy (FRA) bt Andreas Seppi (ITA x21) 5-7, 6-3, 6-2, 6-2
Jo-Wilfried Tsonga (FRA x7) bt Richard Gasquet (FRA x9) 6-4, 3-6, 6-3, 6-2
Andy Murray (GBR x3) bt Gilles Simon (FRA x14) 6-3, 6-1, 6-3