Andy Murray remains on course to become the first man to win successively maiden grand slam titles after defeating a weary Giles Simon in Melbourne.
Having yet dropped a set during the tournament, Murray came into the contest as the overwhelming favourite against a player in Simon who had faced a four hour 43 minute marathon match against fellow countryman Gael Monfils in round three.
The encounter had Simon struggling from the outset but a succession of early breaks contributed to an uncertain start from both players, as Murray failed to recapture the faultless form from the start of his 2013 season.
The British No.1 soon found some rhythm, holding for 3-1 before edging out Simon, who had already conceded defeat in the lead up to the match, 6-3 in the opening set.
The second set following a similar pattern, with neither truly doing justice to the enormity of the contest at the opening slam of the year but it was eventually Murray who took control, opening up a 4-1 lead.
He eventually converted his lead to a two set advantage, taking it 6-1 before an early break in the third all but settled the match.
Simon began to throw in aggressive serves and went for shots early, playing into the hands of Murray, who eventually secured the double break in the final game, winning the set 6-3 and confirming his place in the last eight.
"Obviously no one knew I just have to focus on my side of the court," Murray said. He one of the best movers on the tour but it was tough and grand slams are so physical these days.
"I play Chardy next. He's has two very good wins and I lost against him last time in Cincinnati so that will be tough match."
Murray, who is yet to drop a set on his way to the quarter final, faces another Frenchman in Jeremy Chardy, who knocked out Juan Martin del Potro in round three as the Briton seeks to reach another grand slam semi-final.
The other quarter finals will see Novak Djokovic take on Tomas Berdych and David Ferrer face Nicholas Almagro in an all-Spanish affair. Jo-Wilfried Tsonga will meet with Milos Raonic or Roger Federer.