Meanwhile, Pegula became just the third American woman – behind Williams and Chris Evert – to make back-to-back US Open semis after turning 30, thanks to a 6-3, 6-3 victory over Barbora Krejcikova.
The fourth-seeded Pegula takes a 2-7 head-to-head record into her clash with Sabalenka.
“I think it would be cool to be able to get revenge, obviously,” said Pegula, who lost in two close sets to Sabalenka in last year’s championship match.
Pegula did not have the best build-up to the US Open, winning just two of her six matches after she picked up a third title of the season in Bad Homburg.
She has chosen to peak at the right time though, making it to another semi-final at her home Slam, without dropping a set.
“I just, I guess, surprised myself. I think, at the end of the day, I always come back to the fact that I'm pretty confident with who I am, and I think I'll always back myself and figure things out in the end instead of kind of spiralling and letting it go too far,” said Pegula.
“I think I always catch myself just in time.
“That's what I've been able to do for the last four or five years, being a top player. I feel like I can always come back to the fact that I can figure it out in the end, and that always kind of hits me in the toughest moments of the year.”