The American won 6–7 (5–7), 6–1, 6–3, 1–6, 7–6 (10–8).
The match was not finished until after 3:30 a.m. after 4.5 hours of play. Never before has a match at Flushing Meadows in New York ended so late at night. The second latest came at 2:50 a.m. - when Carlos Alcaraz beat Jannik Sinner in the quarter-finals in 2022.
At the press conference, 23-year-old Ben Shelton praised his Spanish opponent.
"Carlos is one of the greatest champions in our sport at the age of 23. It's always fun to play against him. It's amazing what he can come up with - this was the most enjoyable match I've played in my entire career," Shelton said, according to AFP.
It was also Shelton's first win over a top-three ranked player. Alcaraz, who was world number one, is seeded second at the US Open.
The Spaniard has been out of action for four months with a wrist injury, missing the French Open and Wimbledon before returning to action at the US Open.
The loss to Shelton snapped his 18-match winning streak in Grand Slams. Alcaraz won the Australian Championships in January and before that the US Open last year.
The American has reached the semifinals once before at the US Open, in 2023. In this year's semifinals, he will face compatriot Frances Tiafoe, which means it will be an all-American final. No male player from the United States has won the US Open in 23 years (Andy Roddick).
