“I’ve been [into major quarterfinals] so many friggin’ times,” Pegula smiled on court. “I just kept losing – but to great players, I mean, to girls that went on and won the tournament.

“So I know everyone keeps asking me about it, but I was, like, I don’t know what else to do? I just need to get there again and win the match.

“So thank God I was able to do it. And finally – finally! – I can say semifinalist.”

In terms of ranking, this was not a huge upset, given Pegula had spent the majority of the past two years inside the top five.

And she is perhaps the most in-form player on tour, winning 14 of her past 15 matches after claiming the WTA 1000 title in Toronto and progressing to the Cincinnati final, and now winning another five matches at Flushing Meadows, all in straight sets.

But Swiatek had won six of their past eight meetings, most recently a 6-1 6-0 demolition in the title match at last year’s WTA Finals.

Swiatek had also not dropped a set en route to the quarterfinals in New York and was getting better with each match, outplaying dangerous 16th seed Liudmila Samsonova for the loss of just five games.