Defending champion Sinner needed just 81 minutes to administer a brutal 6-1, 6-1, 6-1 drubbing on Monday to reach the last eight.
Bublik smiled as he embraced Sinner at the net after the defeat, and could be heard telling the Italian: “You’re so good, this is insane.”
Sinner, meanwhile, said Bublik’s performance might have been impacted by his marathon five-set victory in the previous round.
“He had a very tough match the last match, today he didn’t serve as well as he usually serves, and I broke him early,” said Sinner. “Overall, I’m very happy.”
Kazakh 23rd seed Bublik had advanced to Monday’s last 16 clash without dropping a single service game in his three previous rounds, a remarkable 55-game unbroken streak.
But the 6ft 5in 28-year-old’s previously impregnable serve was systematically ransacked by the imperious Sinner, who is chasing his third Grand Slam title of the season in New York.
Sinner went on the offensive in the opening game of the first set, breaking Bublik immediately to set the tone for what would be a lopsided masterclass.
The Italian went on to break Bublik seven more times over the rest of the match as he sauntered into a last eight meeting with 10th-seeded compatriot Lorenzo Musetti.
The one-sided nature of the defeat prompted sympathy from the Arthur Ashe Stadium crowd in the third set, who cheered loudly when Bublik merely won a point as Sinner marched relentlessly towards the finish line.
Even Bublik himself found humour in being so comprehensively outgunned, raising clenched fists in delight after successfully holding serve in the fifth game of the third set.
Sinner is aiming to become the first man to successfully defend the US Open crown since Roger Federer won the last of five consecutive titles in 2008.
The top-ranked Italian has won the Australian Open and Wimbledon titles this season but lost to Carlos Alcaraz in a gruelling five-set battle in the French Open final. (AFP)