Jessica Pegula became the fourth American to reach this year's US Open semifinals on Wednesday by stunning world number one Iga Swiatek as Jack Draper broke through to his first Grand Slam last-four.

Pegula swept past 2022 champion and four-time French Open winner Swiatek 6-2, 6-4 to reach a maiden semi-final at the majors after falling in six quarter-finals.

The 30-year-old will next face Karolina Muchova of the Czech Republic.

If she gets through that she would set-up an all-American title match should Emma Navarro stun world number two Aryna Sabalenka in Thursday's other semi-final.

Draper, meanwhile, became the first British man to make the last four since Andy Murray won the title 12 years ago by beating Alex de Minaur of Australia 6-3, 7-5, 6-2.

The 25th seed will tackle either world number one Jannik Sinner or 2021 champion Daniil Medvedev for a place in Sunday's championship showdown.

Pegula has now won 14 times in 15 matches on US hard courts this summer.

"Finally I can say I'm a semi-finalist. I lost so many of these damn things," said the American after her fourth career win against Swiatek.

"Thanks to the crowd. I sent over a 65mph second serve (on a third match point) because I was so tight.

'Rode momentum'

"I did everything I could to not get frustrated. I took advantage of some things she was not doing so well and just rode that momentum."

Swiatek was undone by 41 unforced errors.

Draper pulled off victory over 10th-ranked De Minaur despite taking a medical timeout early in the second set to have his right thigh bandaged.

"It's amazing. My first time on Arthur Ashe Stadium, it means the world to me," said Draper, who had lost three times in three meetings with De Minaur before Wednesday.

'Best fitness-wise'

"I played a solid match and I feel the best fitness-wise that I have felt in a long time."

Draper has made the semi-finals without dropping a set as he continued an impressive summer run which saw him capture his first ATP title in Stuttgart and then defeat Carlos Alcaraz at Queen's Club on the eve of Wimbledon.

On Wednesday, he sent down 11 aces in his 40 winners while forcing De Minaur to fend off 14 of 20 break points.

The British player enjoys a 1-0 lead over Sinner in the pair's head-to-head although that win at Queen's came three years ago. He lost to Medvedev on clay in Rome earlier this year.

Sinner is the only top-four player left in the men's draw following the exits of Novak Djokovic, Alcaraz and Alexander Zverev.

However, he is yet to reach the last four in New York and faces a test of his credentials against fifth-ranked Medvedev.

Sinner defeated Medvedev from two sets down to win his first major at the Australian Open in January before the mercurial Russian avenged that loss at Wimbledon.

"I will try to think more about Wimbledon than the Australian Open," said Medvedev, also the 2019 and 2023 runner-up at the US Open.

With Frances Tiafoe and Taylor Fritz already lined up for an all-American men's semi-final on Friday, and Navarro and Pegula safely into the women's last four, home fans are dreaming of a title sweep this weekend.

Muchova back in semifinal

Andy Roddick was the last US man to lift a Grand Slam singles trophy in New York in 2003 while Serena Williams, Sloane Stephens and Coco Gauff have triumphed in the women's tournament in the last decade.

Muchova's 6-1, 6-4 win over Beatriz Haddad Maia came despite having to sprint to the bathroom early in the second set, a dash which caught everyone on the hop.

"I had a problem that I wouldn't like to comment on," said the 28-year-old. "Sorry if I disturbed anybody but I really didn't have any other choice."

After losing to eventual champion Coco Gauff in the 2023 semi-finals, Muchova suffered a serious wrist injury which sidelined her until June this year.

A former world number eight, now ranked at 52, Muchova has yet to drop a set, knocking out two-time champion Naomi Osaka and this year's French Open and Wimbledon runner-up Jasmine Paolini.