NEW YORK – Russian veteran Karen Khachanov defeated an ailing third-seeded Felix Auger-Aliassime on Sept 3 in the second round of the US Open in four sets.

Khachanov, unseeded in 2026 but a familiar face in the latter stages of big tournaments, beat Auger-Aliaissime 6-7 (5-7), 6-3, 6-2, 6-2.

The 26-year-old Canadian, a two-time semi-finalist at Flushing Meadows, eked out a first-set tiebreaker against the hard-hitting Russian, who himself made the US Open semi-finals in 2022.

But Auger-Aliassime, who appeared to give up quickly on some balls, was undone by a rash of unforced errors in the subsequent sets. He made 47 in all, compared with 30 for Khachanov.

Khachanov also won several key points with blistering backhand down-the-line winners.

Auger-Aliassime said he began feeling unwell in the middle of the second set.

“I just couldn’t, feel well and was dizzy and seeing spots and couldn’t recover. I thought maybe it would pass, but it didn’t,” the Canadian said after the match.

Auger-Aliassime felt fine the last few days and had no problem before the match on Sept 3.

“I’m going to run some tests and see what comes out of it,” said Auger-Aliassime, who called Khachanov a “great player” but added that he was in no condition to advance.

“I cannot beat him or anybody in this draw feeling the way I felt today. So, if I cannot move, we’re not talking about tennis here. So, it’s unfortunate.”

Khachanov said he noticed after the third set that Auger-Aliassime was “down” physically.

“Let’s say maybe it was physical aspect, maybe not, maybe the heat, I don’t know,” Khachanov said.

“At this point I don’t want to take out the credit from myself because I was staying there fighting three hours and a half ...