How does Andy Murray keep managing to leave us all stunned? He's a 35-year-old with a metal hip, for goodness' sake.

He spent almost five hours on court, saving match point at 5-4 in the deciding set before winning the tie-break 10-6.

Some of Murray's fellow players were glued to screens watching the British three-time Grand Slam champion put in a vintage performance that legendary sports stars and mesmerised fans on social media could find only two words for: Andy Murray.

The magical moments keep appearing for the former world number one - even after the hip surgery that no other singles player had ever returned from.

Many had written him off. Murray himself almost had.

When the Scot burst into tears at Melbourne Park before the 2019 tournament, it was because he thought a hip resurfacing operation - where the head of the femur is covered with a metal cap - would signal the end of his career.

The journey back has been long and arduous. There have been lows - particularly recent defeats at Grand Slams - which left him wondering if all the hard work was worth it.

Therefore, it was apt the latest exhilarating high of his rollercoaster ride came back in Melbourne.

Murray, a harsh self-critic, even allowed himself a pat on the back.

"Over the last few years I've questioned myself at times. There's certainly a lot of people [who have] questioned me and my ability, whether I could still perform at the biggest events and the biggest matches," he said.

"I felt very proud of myself after the match. That's not something that I generally felt over the years at the end of the matches.

"I'm really proud of how I fought through that match when it could have got away from me, how I played in the tie-break at the end.

"I was impressed with myself, which again is not something I often do. I'm hard on myself usually."

'You can see the gladiator in him'

Against Berrettini, Murray displayed all of the qualities which have endeared him to many over the years.

Fight. Determination. Grit.

It almost sounds trite reeling off the same adjectives. But these characteristics - and his never-say-die attitude - were there again for all to see.

One example came when Murray - he has a metal hip, remember - dived for a volley in the fourth set tie-break which would have teed up a match point.

It floated just long and led to loud gasps, partly of excitement and partly of concern.

Even Tim Henman, another British great, asked him what everyone was thinking: should a man of Murray's age, one with a metal hip, really be doing that?

'I'll probably find out tonight or tomorrow whether that was the right move," Murray laughed during an interview on Eurosport.

"But I was so close to the finish line there, I probably should have made the volley."

Novak Djokovic, the 21-time major champion who has known Murray since they were 12-year-olds playing in junior competitions, had his eyes fixed to a television screen in the locker room and looked almost incredulous at what he was seeing.

Dan Evans, a British Davis Cup team-mate, lived the emotions of a super fan. A super fan stretched out on a gym ball after finishing his match a short time before.

Their reactions echoed those inside Rod Laver Arena as Murray produced shots and points which few thought he could still pull off.

Coco Vandeweghe, a two-time Grand Slam singles semi-finalist watching for BBC Radio 5 Live, said people simply "can't not watch Murray".

"You see the gladiator in him - the blood from his knee, the sweat, hobbling around," she said.

How will Murray recover now?

Murray's longevity has been down to the "professionalism" he puts into "every aspect of his day", says former British number one Annabel Croft.

"He never gives up. What he really wants is to play like that in a Grand Slam match, taking on a big name. It is a huge moment," said the BBC Radio 5 Live analyst.

"What is going to be interesting now is how he pulls up tomorrow. The team will spend a lot of time on the body before his second-round match."

The work to ensure he will be in a fit state to face Australia's Thanasi Kokkinakis or Italian veteran Fabio Fognini on Thursday continued well into Tuesday night.

After the customary post-match ice bath, Murray got a good meal down him and planned to have more physio treatment at his hotel.

Most importantly, he would try to get an early night - one of the key changes he has made in recent years.

"The one thing I've definitely got better, probably since I had the kids, I used to always go to bed quite late," he said.

"Now I tend to get myself in bed much, much earlier - prioritise my sleep a bit more and the process of the recovery.

"I wouldn't expect myself to feel perfect on Thursday, but hopefully I'll be in a good place."

'Mad respect for big lungs'

Murray's latest remarkable performance led to stunned reactions from fellow players, high-profile footballers and journalists...

...and the fans using #bbctennis to express their admiration.

Andy Moore: Sir Andy Murray - incredible performance! To do what he does after the injury he had is just outstanding. Might not quite be the same player he was but you never lose that desire and hard work!

Drewett Matthew: Andy Murray, you are superhuman.

Steve Kilner: He's got a metal hip and he's just played almost five hours of tennis, against a top-20 opponent, winning 29 games, including a match tie-breaker... silly, ridiculous, brilliant, sublime. There is only one Andy Murray.

Saadia: Take a bow Andy Murray. Huge respect. Well done champ.