Aryna Sabalenka came from a set and a break down to deny the US Open crowd an all-American final.
The second seed, who will rise to world number one on Monday, lost the first set to love against Madison Keys, but hit back to win 0-6 7-6 (1) 10-5 and book a Saturday showdown with Coco Gauff.
Keys had slipped under the radar at this year’s championships, but she announced herself inside Arthur Ashe Stadium as she raced through the first set in just 30 minutes.
The 17th seed went 4-2 up in the second and served for the match at 5-4, only for Sabalenka to break her to love and begin the comeback.
When Sabalenka got to 7-3 ahead she thought she had won the match, forgetting it was now first to 10, and dropped her racket in delight.
She managed to refocus, though, and wrapped up the victory in two-and-a-half hours.
Sabalenka said: “I thought we played a tie-break up to seven. I was all over the place. Thanks team for reminding me it’s up to 10.
“She played incredible tennis, another level. Somehow, I don’t know how actually I turned around this match. Being in the final of the US Open for the first time means a lot.”