Before the final major of the season began, everyone wondered who could stop Alcaraz or Sinner sweeping the Slams for the second straight season.
Alcaraz has won back-to-back French Open titles and lifted the Wimbledon title last year, before losing to Sinner in this year’s final. Now he has booked his place in the New York showpiece without dropping a set.
He broke Djokovic in the first game of the match and threatened to move a double break ahead before the Serb served his way out of trouble.
It was not a classic set of tennis, lacking absorbing rallies as points were punctuated by baseline errors. Nevertheless, Alcaraz never looked like relinquishing his lead.
Momentum switched at the start of the second set, however – just as it did in their Australian Open quarter-final in January.
Alcaraz dominated the first set in Melbourne, became confused as Djokovic upped the intensity in the next, and ultimately malfunctioned in a four-set defeat.
Thoughts went back to that match when Djokovic moved 3-1 up in the second set. But this time Alcaraz recognised what was happening and was able to adjust tactically and mentally.
The Spaniard ended a brutal exchange at 30-30 by casually flicking a cross-court forehand past Djokovic, bringing up a break point that his deflated opponent planted in the net.
Neither player created any more break chances, leading to a tie-break where Djokovic wiped out a 4-1 deficit for 4-3 before running out of steam.
Alcaraz had not previously lost any of the 52 Grand Slam matches where he had won the opening two sets.
It quickly became apparent that Djokovic, who asked for treatment on his neck before the third set, would not be the one to end that run.