After celebrating with his team, the victor wrote a message on the television camera, "fino alla fine" - Italian for "until the end" - a slogan used by Juventus, the football club Musetti supports, and one that perfectly matches this performance.
Musetti missed out on ATP Finals qualification when he lost to Novak Djokovic in Athens on Saturday but was drafted in to make his debut when the Serbian withdrew.
He had little time to recover before Monday's 6-3 6-4 loss to last year's finalist Taylor Fritz, and was back in action again on Tuesday knowing defeat would bring elimination.
Musetti took the first set without conceding a break point and had De Minaur on the rails in the second set opener only for the Australian to survive and go on to force a decider.
The Italian's loss to Djokovic took almost three hours, and was the third three-setter Musetti had played last week in Athens. A third set against De Minaur seemed one too many when the Australian took a 2-0 lead.
"I was really struggling physically because Alex raised the level and intensity and I was really struggling to find the solution," Musetti said.
The Italian crowd roared on encouragement at every point won by Musetti, and even some that were lost, like when De Minaur hung on to win a 31-shot rally, holding serve to go 5-3 up.
Musetti pulled out a cheeky through-the-legs shot, but De Minaur, falling backwards, somehow won the point and both players collapsed to the floor.
It looked like Musetti had lost his chance, but he went on to win the next four games and claim the match, beating his chest after winning dramatic points and rallying the crowd who needed little encouragement.
"I'm a warrior," Musetti said.
"I have improved a lot on the mental side and I am pushing myself to the limit because I am playing every match against the top players.
"At the end with a big heart and big passion for this game, I don't know from where, I started to feel better and play better and the support of the crowd is amazing."
It does not get any easier for Musetti, with the Italian facing world number one Carlos Alcaraz on Thursday, where again a win is needed to survive against a player who has won both his matches.
One thing is for certain, nobody will be leaving the Inalpi Arena early, now that Musetti has shown what "until the end" really means.