Jessica Pegula will take on Karolina Muchova with Emma Navarro up against Aryna Sabalenka in the semi-finals of the US Open - live on Sky Sports Tennis from 7.30pm on Thursday.
Pegula knocked out the world No 1 Iga Swiatek 6-2 6-4 to reach her first major semi-final against unseeded Czech Muchova, but first on Arthur Ashe Stadium it is American 13th seed Navarro up against favourite Sabalenka for a place in Saturday's women's singles final - from midnight.
Playing in her seventh quarter-final at majors, sixth-seeded Pegula took advantage of Swiatek's wobbly forehand, to close out the biggest win of her career in front of the home crowd at Arthur Ashe Stadium.
Looking ahead to her clash with Muchova, the American said: "She's so good, so talented, so athletic. I love how she just doesn't play and comes back and beats everybody.
"I know she has a lot of experience going deep in Slams so I'm gonna have to bring my best tennis. I'll worry about that when I wake up in the morning."
Muchova, in only her sixth tournament back after suffering a wrist injury at the 2023 US Open, overcame illness to beat Brazil's Beatriz Haddad Maia 6-1 6-4 to reach the New York semi-finals for a second consecutive year.
The Czech, who has not dropped a set at the year's final Grand Slam, received medical treatment and had to leave the court four times for comfort breaks, but she still did the business.
She is still in the early stages of a comeback from a serious injury, where she spent 10 months on the sidelines following wrist surgery, only returning in June.
And she is making up for lost time in New York, looking as good as anyone left in the draw and still yet to drop a set in the tournament.
A tough test lies ahead in the shape of home favourite Pegula next for Muchova, but she will be confident going into the match, providing her health concerns clear up.
"A little weird match I have to say, I have some problems I don't want to comment on if that's OK," she said on court.
"I am happy to manage it, running to the bathroom and back, sorry if it disturbed anyone but I had no other choice.
"I am really happy to be in the semi-final, I wouldn't have said that before the tournament. Every round gets more difficult and I am sure it will be a difficult match."
The first semi-final - starting at midnight live on Sky Sports Tennis - will see Navarro play Sabalenka for a spot in the final.
Navarro followed up her fourth-round win over defending champion Coco Gauff with a straight-sets success over the Spaniard Paula Badosa to reach a Grand Slam semi-final for the first time.
Sabalenka displayed a typically powerful performance to get into the semi-finals in New York for the fourth year in a row after crushing Olympic gold medallist Qinwen Zheng.
For the first time in 21 years, two American men and two American women will play in the US Open singles semi-finals with Taylor Fritz and Frances Tiafoe set to meet for a place in the men's final on Friday.
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Order of Play (all times UK)
Arthur Ashe Stadium
From 8pm - Mixed doubles final
Taylor Townsend & Donald Young vs Sara Errani & Andrea Vavassori
From midnight - Women's singles semi-finals
Emma Navarro (USA) (13) vs Aryna Sabalenka (2)
Jessica Pegula (USA) (6) vs Karolina Muchova (Cze)
What's coming up on Sky Sports Tennis in September?
- Jasmin Open, Tunisia - WTA 250 (9-15 September)
- Guadalajara Open, Mexico - WTA 500 (9-15 September)
- Korea Open - WTA 500 (16 -22 September - with Emma Raducanu in action)
- Thailand Open - WTA 250 (16 -22 September)
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