American Frances Tiafoe pulled off a remarkable comeback to upset fifth seed Andrey Rublev 4-6 6-3 7-6(6) 4-6 6-1 in a see-saw encounter to move into the fourth round of the U.S. Open on Friday.

In a match that lasted nearly four hours and finished at 2:15 am local time, Tiafoe was spurred on by the home crowd after many stayed behind to cheer every point won by the 23-year-old.

"You guys are the reason I got it done tonight. You guys stuck with me all the way through," Tiafoe said in his on-court interview.

"I love these matches... these are the matches I train for. I came out here thinking 'I want to beat him'. Let's keep going."

After Rublev took the opening set on the back of a strong service game, Tiafoe bounced back in the second to keep the match evenly poised.

The American saved a set point in the third set tiebreak before going 2-1 up and despite the sparse crowd still in attendance, the roar was deafening.

Rublev regained his momentum in the fourth when, at 4-2 down, he won four consecutive games to force a decider.

But Tiafoe found an extra reserve of energy in the fifth where his forehands were faster and stronger, giving Rublev no chance to settle down as the American quickly jumped into a 5-0 lead before serving out the set.

"I've lost a lot of five-setters. I was just amped up... I wasn't going to leave this court without winning tonight," Tiafoe, who finished with 69 winners and 23 aces, added.

Up next for Tiafoe is Canadian Felix Auger-Aliassime, who beat Roberto Bautista Agut 6-3 6-4 4-6 3-6 6-3.

"Felix is another great friend of mine, but I'm coming for him."