Home favourite Jessica Pegula staged a stunning comeback to set up an enticing US Open final against world number two Aryna Sabalenka.
American Pegula came back from a set, a break and break point down to see off Karolina Muchova 1-6 6-4 6-2 and reach a first major singles final.
She will now face Sabalenka, who powered into the final for the second year in a row with a 6-3 7-6 (7-2) victory over American Emma Navarro 6-3 7-2.
The Belarusian is the first women's player since the great Serena Williams in 2019 to reach back-to-back singles finals at Flushing Meadows.
Sabalenka will be greeted by a wall of noisy support for New York-born Pegula on Saturday - but she already has experience in that area, having jokingly admonished the crowd for cheering for Navarro.
"Well now you're cheering for me, it's a bit too late," Sabalenka said as she began her post-match interview.
"It really means a lot and even though you guys were supporting her still I had goosebumps for you cheering.
"Margaritas for everyone!"
Pegula had previously lost her past six major quarter-finals before beating world number one Iga Swiatek on Thursday, and she followed that up with a battling victory over Muchova.
"I came out flat but she was playing unbelievable, she made me look like a beginner," Pegula said.
"I was about to burst into tears because it was embarrassing, she was destroying me.
"I don't know how I turned that around, honestly."
Poland's Swiatek is the player at the top of the world rankings, but arguably Sabalenka is the best hard-court player in the world.
Always a powerful player, Sabalenka struggled for years with her serve, ultimately deciding to work with a biomechanics expert to cut down the number of double faults.
That helped her win two Australian Open titles, but this year has seen her move up a gear mentally, able to block out the crowd noise and shrug off errors and momentum swings better than usual.
Her easy power was on show against Navarro - she hit 34 winners to the American's 13 - but she also made the same amount of unforced errors.
Navarro, who took out Gauff in the fourth round, is a crafty, intelligent player, who gradually adjusted to absorb Sabalenka's heavy blows.
The two traded early breaks a pounding Sabalenka forehand gave her a 4-2 lead and, after seeing off a break back point, she served out the first set.
She was merciless on Navarro's second serve, again going an early break up, but as the finish line came into sight, Sabalenka's nerves showed and she was broken when serving for a place in the final.
However, her quality showed in the tie-break, with the second seed reeling off seven points in a row to see off Navarro.
Afterwards, Sabalenka said she thought back to last year's final, where she was visibly distracted by the noisy support for Gauff.
"I had really tough lessons here in the past. I wasn't ready, then I got emotional, then I just couldn't handle the crowd," Sabalenka said.
"I'm still hoping to hold that beautiful trophy."