Andy Murray couldn't quite remember the last time he smashed a racket.

But he certainly didn't forget how to crack the frame with one lethal strike after wasting four match points at the end of the third set of his fourth-round win over Stephane Robert at the Australian Open on Monday.

There's an art to smashing a racket properly, he said.

"A lot of guys sort of hold it by the throat and kind of throw it face down. That's how you would throw it if you didn't want to break the racket," he said. "Whereas if you just kind of go flat with the frame or if you just hit the frame like that, the racket's gone straight away."

Murray's racket was gone straight away.

"I don't feel like I killed it, but it won't be getting used again," he said with a half-smile during his post-match news conference. "Sometimes it's necessary, you know."

The source of Murray's irritation was his loss of focus during the third set of his match against Robert, a No. 119-ranked journeyman who was the first "lucky loser" to reach the fourth round at the Australian Open.

Murray had cruised through the first two sets, but in the third, he suddenly couldn't win a point on the Frenchman's serve. He double-faulted on game point — twice. And then he double-faulted on match point, one of four match points he blew before Robert captured the set in a tiebreaker to force a deciding fourth set.

Murray had 27 unforced errors in the third set, compared to just four in the first. But he rallied in the fourth the close out a 6-1, 6-2, 6-7 (6), 6-2 win.

"I put a lot of hard work into that third set. I maybe lost concentration when I served for it," he said.

The fourth-seeded Scot is working his way back into top form after undergoing minor back surgery in September and sitting out the past four months. Consistency is still an issue, as his third set against Robert showed.

Fortunately for Murray, a three-time finalist at the Australian Open, he has been relatively untested in Melbourne so far this year. Three of his four matches have been against players ranked outside the top 100.

His next match, however, will present a far greater challenge — No. 6-seeded Roger Federer, who defeated Jo-Wilfried Tsonga in another fourth-round match on Monday.

Murray has an 11-9 edge over Federer in their head-to-head matchups. The Scot also won their last encounter — a five-setter in the semifinals of last year's Australian Open.

"I said at the start of the tournament, I can't honestly say my expectations are as high as if I'd been playing for the last four months," Murray said. "But I'm not far away from winning the event. Anyone's that's in the quarters is close."