The Australian went toe-to-toe with the American No. 1 all afternoon, blasting 74 winners and sending down 19 aces in a thundering performance that left the capacity crowd on John Cain Arena in raptures.
Crucially, Poprin had the chance to wrap up the match in the fourth set; despite being 3-5 down in the tiebreaker he fought back to get a look at one match point, but Fritz held his nerve to save that, take the set and force a decider.
But Popyrin was too strong in the fifth, winning, 6-7(4), 7-6(2), 6-4, 6-7(6), 6-2 in what is the biggest win of the 23-year-old’s career.
It’s Popyrin’s second straight five-set victory, after he defeated Chun-Hsin Tseng in the first round.
Popyrin was emotional on court after the win, joining in a “POPY” chant with crowd, before thanking them for their support.
He said he was proud of the efforts he put in during the offseason which has allowed him to close out big matches.
“Oh my god, this is crazy man,” he said of the win.
“Pre-season I put my head down and worked as hard as I possibly could.”
Fritz did tke time off the court for a medical timeout between the third and fourth sets, however didn’t appear to be negatively affected for the rest of the match.
Popyrin will face another American, world No. 89 Ben Shelton for a place in the fourth round on Saturday.