Jessica Pegula stunned world number one Iga Swiatek at the US Open to secure her place in a long-awaited first Grand Slam semi-final.
American Pegula had lost her past six major quarter-finals but she overwhelmed Polish top seed Swiatek 6-2 6-4 in New York.
She will face Karolina Muchova on Thursday for a place in the final after the Czech beat Beatriz Haddad Maia 6-1 6-4.
"I've been [to the quarter-finals] so many freaking times but I kept losing," Pegula said.
"Finally - finally - I can say I'm a semi-finalist. Thank you to the crowd, you carried me through that last game.
"To do it at prime time against the number one player in the world - it's crazy, but I knew I could do it."
Pegula's success caps a strong showing for Americans at their home Grand Slam, with compatriot Emma Navarro facing Aryna Sabalenka in the other semi-final.
There is also guaranteed to be an American man in the singles final, with Taylor Fritz and Frances Tiafoe meeting in the last four on Friday.
It was an uncharacteristically lacklustre performance by 2022 winner Swiatek, who made 41 unforced errors as she struggled to control her forehand in particular.
By contrast, Pegula was locked in from the start and broke in the opening game, courtesy of a Swiatek double fault.
Another gave Pegula her second break to go 3-0 up in a flash and she proceeded to take the first set in just 37 minutes.
The 30-year-old New Yorker continued to delight her home crowd, with her crisp, accurate groundstrokes keeping the pressure on Swiatek.
There was an improvement from Swiatek in the second set and, having been broken again, the Pole hit back immediately.
But Pegula kept up the pressure and secured the decisive break at 3-3 before she pressed on towards victory.
Nerves finally emerged as Pegula served for the match but she converted her third match point to secure a place in the semi-finals.
Muchova overcomes illness to beat Haddad Maia
Muchova overcame illness to reach her second consecutive US Open semi-final with a straight-set win over Haddad Maia.
Muchova, who only returned to action in June after having wrist surgery, first left the court after wrapping up the first set with ease.
The unseeded 28-year-old then ran off court at 2-1 and again at 3-2 in the second and was seen by the doctor and physio at 4-3.
"It was a weird match," said Muchova. "I had some problems I don't want to comment on but I had to keep running to the bathroom and back.
"Sorry if it disturbed anyone but I had no other choice."
Haddad Maia also had problems and seemed to be in tears before receiving treatment from the doctor at 5-3 down in the second set.
BBC