By Nick Mulvenney

MELBOURNE (Reuters) - Third seed Milos Raonic came safely through a potentially tricky match against Roberto Bautista Agut 7-6(6) 3-6 6-4 6-1 on Monday to reach the Australian Open quarter-finals for the third straight year.

The Canadian, the highest surviving seed after the early departures of Andy Murray and Novak Djokovic, rarely hit his usual heights in the two hour, 52 minute contest on Hisense Arena.

The 26-year-old produced his best tennis when it mattered, though, coming back from 5-1 down in the tiebreaker to win the first set and finally got some breathing space by saving break points and breaking the world number 13 to win the third set.

Teak tough Bautista Agut is nothing if not a fighter but required treatment on his left leg before Raonic raced away with the fourth set and sealed the victory with a crunching forehand winner down the line.

"I guess there's always that sort of match where you sort of fall off," Raonic told reporters.

"It's a long two weeks. So I guess unfortunately that was it for me today. So I'm happy I was able to solve that."

The match was a stop-start affair because of a few passing showers and it was only when Raonic insisted the roof be closed that the Canadian stamped his authority on the match.

Raonic had complained of a fever after his third-round victory and looked flat in the opening set before coming alive to win the tiebreaker and taking a service break to open the second.

"I still don't necessarily feel at full capacity," he added. "I have energy now. I can go about my days normally. Sort of on the tail end of the recovery."

Bautista Agut enjoyed good fortune when his running pass took a deflection off the net tape to allow him to break back and the Spaniard rattled off five of the next six games to even up the contest.

The third set was a cat-and-mouse affair until Raonic again ramped up his game to secure the break he needed to go 2-1 up and Bautista Agut was barely able to draw breath before he was 5-0 down in the fourth.

Raonic, who fired down 33 aces and 75 winners, will next meet 2009 champion Rafael Nadal or Gael Monfils as he continues his quest for a maiden grand slam title.

Even with Murray and Djokovic gone, though, he was looking no further ahead than his next match.

"I just know who I play next, I don't know who I was supposed to play and this kind of stuff," he said.

"I'm pretty intent on staying in that moment."

(Editing by Ed Osmond)