Italian top seed Jannik Sinner took down ailing Briton Jack Draper 7-5, 7-6(7/3), 6-2 to reach the US Open final on Friday, overcoming muggy conditions at Arthur Ashe Stadium.
Sinner appeared to have suffered a wrist injury when he fell over in the second set but rallied to reach his second major final after winning the Australian Open earlier this year.
Little went right for Draper, who vomited three times in the second set as he struggled with the heat and humidity that also left his shirt soaked in sweat.
Ten double-faults also failed to help the 22-year-old's bid to reach a Grand Slam final for the first time.
"It was a very physical match as we saw. I just tried to stay there mentally," said Sinner, who has survived the intense pressure of being the overwhelming favourite to win his first US Open title following the early exits of Novak Djokovic and Carlos Alcaraz.
Sinner will play the winner of an all-American semifinal between Taylor Fritz and Frances Tiafoe on Sunday.
Sinner and Draper traded early breaks in the first set but the momentum swung in the Italian's direction when the Briton dropped serve in the 11th game with a double-fault.
Draper held his serve through a marathon four-deuce opening game in the second set but could not convert a break point chance in the second game. From then on, the contest turned into a nightmare for the 25th seed.
Jack Draper was struggling on a hot, humid day at Flushing Meadows, throwing up several times in his match against Jannik Sinner. (Getty Images: Al Bello)
The Briton dropped his racket and ran to his bench to change his sweat-drenched shoes after the sixth game and he threw up twice in the eighth game, waving off the umpire's attempts to pause the match and bring out a crew to clean the mess.
Sinner looked to be in trouble after he slipped and fell in the ninth game, wincing in pain after bracing himself with his left hand in the fall.
One physio came to massage the Italian's wrist while another came to help the ailing Draper during the changeover.
Draper requested another set of fresh shoes from his locker and battled on, vomiting for a third time in the 12th game before Sinner sprinted through the tie break.
Sinner got the critical break in the final set with a terrific backhand winner down the line in the sixth game and Draper looked miserable as he sipped a soda on his bench after the seventh game.
Sinner closed it out with a backhand winner on match point, embracing his opponent at the net.
In the other semifinal, Taylor Fritz survived an epic fight against American compatriot Frances Tiafoe 4-6, 7-5, 4-6, 6-4, 6-1 to reach his first major final.
The home fans packed Arthur Ashe Stadium for the all-American semifinal, where 12th seed Fritz used his monster serve to his advantage, closing out the match with one of 16 aces.
Tiafoe got off to a terrific start but gradually ran out of energy and had nothing left in the tank in the final set, as 50 unforced errors and nine double-faults across the match cost him dearly.
Fritz will face Sinner on Monday morning, Australian time, as he tries to end a 21-year US men's major drought dating back to Andy Roddick winning the US Open in 2003.
Reuters