A point away from losing the second set with his opponent serving, Frances Tiafoe looked at a positive.

At least, he figured, he would be able to change out of his sweaty shirt and sneakers. A couple of minutes later, he hadn't changed his clothes. He had changed around the match.

Tiafoe rallied to steal the second set and went on to earn his way back to the US Open quarter-finals for the third straight year, beating Alexei Popyrin 6-4, 7-6 (3), 2-6, 6-3 on Sunday night. Popyrin is the No. 28 seed from Australia who upset defending champion Novak Djokovic on Friday to reach the fourth round of a Grand Slam for the first time.

“I think the second set was a huge, huge win for me,” Tiafoe said. “You know, 5-3, 40-love, him serving, how good he serves, that was really, really big. To break there and then to win that set was huge.”

Alexei Popyrin Reuters

The No. 20 seed will attempt to match the best Grand Slam result of his career when he faces No. 9 Grigor Dimitrov on Tuesday for a berth in the semi-finals.

Tiafoe lost to eventual champion Carlos Alcaraz in that round in 2022, and was eliminated last year in the quarter-finals by Ben Shelton.

Tiafoe is the first American man to reach three consecutive US Open quarter-finals since Andy Roddick from 2006-08. Pete Sampras and Andre Agassi are the only other American men since 2000 to reach the final eight in New York three straight times.

Tiafoe said an unexpected pep talk from Serena Williams inspired him like never before.

"Telling me she's always following no matter what, telling me it's so good to see now that I'm done, you're the guy of colour playing and doing well," he said.

"I'm, like, damn. That's really, really cool that she sees me as that."

Six-time champion Williams set Flushing Meadows abuzz on Saturday when she returned to the tournament for the first time since playing her final match at Arthur Ashe two years ago.

She was spotted again on Sunday, sipping the tournament's signature "Honey Deuce" cocktail and taking in the action.

"It was really cool to have her want to talk to me before a match and really say she wants me to do this thing and that I'm capable of doing it," said Tiafoe.

"I don't think it will hit me like that if anybody else said it to me."