A series of composed performances had seen Draper break new ground in New York, moving into the semi-finals without dropping a set.
While he had played cooly and clinically, there was a question mark about how the left-hander would fare against an opponent of Sinner’s class.
Draper’s first four opponents were ranked below him – and he avoided playing Spanish superstar Carlos Alcaraz in the third round following the French Open and Wimbledon champion’s shock defeat in round two.
Quarter-final opponent Alex de Minaur, seeded 10th, was hampered by fitness problems, too.
In the opening exchanges of the semi-final, Draper pushed Sinner – who has seemingly put the controversy of testing positive for a banned substance earlier this year behind him – but three double faults proved costly as the Italian broke decisively for 6-5.
Then, tension mounted for Draper in a bizarre second set.
While clearly struggling, he continued to hang onto his serve in the face of four break opportunities for Sinner before twice being sick on court after points.
In a madcap ninth game, his vomit caused the match to be briefly paused while the surface was cleaned, before 23-year-old Sinner fell retrieving a return near the advertising board behind the baseline and damaged his left wrist in the process.
Both men required treatment at the same time – a rare sight.
Sinner upped the ante in the tie-break, thumping groundstrokes to push Draper back behind the baseline, and drawing mistakes to move into a two-set lead.
The uphill task facing Draper – watched on by his family, including mother Nicky whose flight from London landed in New York at 2am earlier on Friday – appeared insurmountable.
Draper showed resilience to continue fighting against the best player in the world, refusing to retire like he had to do on several occasions earlier in his career.
But his resolve finally wavered as Sinner rattled off the final four games to secure victory in three hours and three minutes.
“Jannik plays at such a high level all the time. I had chances here and there and I didn’t take them,” said Draper.
“I obviously wasn’t feeling my best and struggled at certain periods of the match, but Jannik beat me fair and square.”