A proud Andy Murray said he "gave everything" as his 4:05 am finish caught up with him in a typically defiant third-round loss at the Australian Open on Saturday.

The 35-year-old bowed out to 24th-seeded Spaniard Roberto Bautista Agut 6-1, 6-7 (7/9), 6-3, 6-4, but was given a huge ovation by an appreciative Melbourne Park crowd.

Britain's Murray was clearly feeling the effects of his epic five-setter in round two, which started on Thursday but ended in the early hours of Friday.

Now ranked 66th and sporting a metal hip, the former world number one said he took "great memories" from the first Grand Slam of the year.

The three-time major champion admitted having "mixed emotions", saying: "I gave everything that I had the last three matches — I'm very proud of that.

"But I'm also disappointed because I put loads of work into the beginning of this year and was playing well enough to have a really good run, have a deep run."

Murray did not look to make excuses, but said that after two five-setters to get to round three and his early-morning finish against Australia's Thanasi Kokkinakis "my feet didn't feel great".

The epic five-setter in round two had lasted a gruelling five hours and 45 minutes — the longest match of Murray's storied career.

"My legs were actually okay," he said. "They weren't too bad, but I was struggling with my lower back. That was affecting my serve."

Murray, who looked all set to retire four years ago before undergoing career-saving surgery, was 3-0 down in a flash in the first set against Bautista.

But he had Margaret Court Arena firmly in his corner and a huge cheer went up when he finally got on the board, holding serve for 3-1.

It was to be only a temporary reprieve as the Spaniard raced away with the first set in a lopsided 29 minutes.

Murray held serve to start the second set but he appeared sluggish.

He committed a double fault to go 2-1 behind in the second set, Murray letting out a howl of frustration.

Five-time Australian Open runner-up Murray has made a career of dramatic comebacks and he threatened one again as he broke back for 4-4.

Murray does not know when to quit. His opponent then had two set points in the second-set tiebreak, only for Murray to roar back to win 9-7 and claim the set.

Bautista got the break to take the third set, but Murray would not go away in the fourth, even as the match stretched past three hours.

Then came the killer blow as the 34-year-old Bautista broke Murray for a 5-4 lead, then sealed the deal on his first match point when the Briton fired a return into the net.

Bautista faces unseeded Tommy Paul of the United States in the last 16.

Murray has every intention of keeping going, even as age and injuries catch up with him.

"I can have a deeper run than the third round of a Slam, there's no question about that," he said.