Sinner’s defeat extends the longest drought without a successful men’s title defence of any Grand Slam in the Open era.
No man has retained the US Open crown since Roger Federer won five in a row from 2004 to 2008.
Anticipation for the third straight Grand Slam final between the sport’s top two players assumed an even greater dimension with the presence of Trump.
It was the latest in a series of visits to major sporting events for the US leader after his trip to the NFL’s Super Bowl in February and the Fifa Club World Cup final in July.
He appeared before the playing of the Star-Spangled Banner, waving to the crowd, which greeted him with a mix of cheers and boos. He was given a frostier reception later in the match though when shown again on the stadium’s big screens.
A constellation of showbiz and sports icons turned out as well, with rock star Bruce Springsteen, fashion icon Tommy Hilfiger, actor Michael Douglas and basketball superstar Stephen Curry all on hand.
The start of the final was pushed back 30 minutes to allow fans additional time to enter Arthur Ashe Stadium as a result of tighter security measures in effect because of Trump’s attendance.
Even then the 23,000-capacity venue was no more than three-quarters full when Alcaraz broke Sinner in the opening game of the match.
As he did in the Wimbledon final, Alcaraz pinned Sinner on the back front early and broke a second time for a 5-2 lead before serving out to love.
With hundreds of spectators still waiting to get in at the start of the second set, Alcaraz sought to hammer home his advantage.
He created a break point but Sinner hung on and stalled Alcaraz’s momentum, belatedly ramping up his game and surging 3-1 ahead as the Spaniard suffered a brief dip on serve.
Sinner levelled the contest at a set apiece but Alcaraz stormed back with another break early in the third, wriggling out of a tight spot on serve with the help of a sensational baseline smash that sliced away from his rival for a 3-0 edge.
He padded his lead with another break and quickly wrapped up the set, keeping his foot down to corner Sinner again to begin the fourth set.
This time Sinner saved two break points but Alcaraz made another charge in the fifth game, delivering the decisive blow for an advantage he never relinquished as the Spaniard became only the fourth man to win multiple majors on hard court, grass and clay.
