World number 50 Khachanov, who lost the ‌opening match in his three US Open tune-up events, was far from spectacular ‌but did enough on a day when 2025 semi-finalist Auger-Aliassime ‌struggled mightily.

Khachanov, who made a run to the US Open semi-finals ‌in 2022, broke Auger-Aliassime's serve seven times on the ‌Louis Armstrong Stadium court and saved seven of the nine break points he faced en route to securing only his second top-10 win at ‌a Grand Slam.

Auger-Aliassime looked ready to whip ⁠through the first set ‌after consolidating a break for a 3-0 lead but was suddenly ​undone by a string of errors, allowing Khachanov to pull ahead before the Canadian broke for a second time ​to get to 4-4.

But Khachanov showed he was ready for a fight and twice held at love while serving to stay ⁠in the set before ​falling short in the tiebreaker, which ended when he sent a backhand long after chasing down an Auger-Aliassime volley.

In the second set, it was Khachanov's turn to jump ahead 3-0, but he ‌never looked back, ultimately closing it out on his serve after coming back from 15-40 down.

Khachanov cruised through the third set, breaking at love to reach 4-1 en route to wrapping up the frame on his serve and leaving Auger-Aliassime with a long road back on a day when little was going right for him.

The Russian, displaying full confidence in his swings, wasted little time in the fourth set, ‌opening up a 4-0 lead that appeared to drain the ​energy and strength from Auger-Aliassime, who looked a shell ‌of his normal self.

Khachanov went on to close out the encounter with a four-point hold, the final blow coming with a massive serve that Auger-Aliassime failed to return.

Up next for Khachanov, who has only reached two quarter-finals this ⁠year, will be either ⁠Frenchman Benjamin Bonzi or Peruvian ‌32nd seed Ignacio Buse.