It was the 35-year-old’s first win over a top-20 player since his hip problems began in 2017.
Here, the PA news agency looks at how Murray’s fitness has improved.
The two-time Wimbledon champion, who underwent hip resurfacing surgery in 2019, admitted late last year he had allowed his famously stringent standards regarding his physical condition to slide.
The Scot had been suffering with cramping and was also unhappy with aspects of his game.
But he addressed both during a period training with coaches Ivan Lendl and Mark Hilton and physio Phil Hayward in the United States during pre-season.
In a three-week boot camp in Florida, Murray practised every day as well as building his fitness.
He revealed: “I put a lot of work in on the court. I did a lot of cardio work on the bike and on the versaclimber. I was totally focused on my training and on my tennis, the things I needed to do to get better.
“It’s something that I’ll definitely look to do at times during the rest of this year to make sure I dedicate enough time to the hard work and improving my game.”
The results are clear to see. Against Berrettini, Murray seemed to moving better than at any time during the last four years, certainly as he took the first two sets.
And as the match wore on he was still zipping along the baseline, retrieving drop shots and at one point diving at the net for a volley, proving that the rigorous fitness programme is paying off.
Not bad for a guy with a metal hip.
Italian Berrettini was probably the better player over the final three sets but that is when Murray had to dig in.
Having come through five sets, including two tie-breaks (the second a first-to-10 match tie-break) Murray showed he can match the stamina of the top players.
His level dipped slightly in the third but at the end he was still able to race into a 5-0 lead in the deciding tie-break.
Never in any doubt. Murray’s appetite for a battle is as strong as it was in his heyday and which saw him reach world number one in 2016.
He saved a match point against Berrettini and fed off the crowd with fist pumps galore as he rolled back the years in Melbourne.
It was for days like this that Murray went under the surgeon’s knife rather than admit defeat and retire.