De Minaur lived up to his 'Demon' nickname, showing energy and character as he hustled the lethargic-looking American all over the court, and after taking the first set tiebreak, stormed to victory following an early break in the second set.
A victory for Spanish world number one Alcaraz against Musetti in the other Jimmy Connors Group match would send De Minaur into the semi-finals along with Alcaraz, but a Musetti win would see the Australian exit the season-ending championships.
Alcaraz is now assured of his place in the semi-finals, win or lose, though defeat would put him in second place in the group, while a win would guarantee the Spaniard the year-end world number one spot ahead of Italy's Jannik Sinner.