New York, New York - Jannik Sinner closed in on his second tennis Grand Slam title of 2024 on Wednesday when he reached his maiden US Open semi-final as Jessica Pegula stunned Iga Swiatek to complete a rollercoaster year for the world number one.

Top seed Sinner defeated 2021 US Open champion and two-time runner-up Daniil Medvedev 6-2, 1-6, 6-1, 6-4.

He will take on 25th-ranked Jack Draper for a place in the final after the British player made his first semi-final at the Slams with a 6-3, 7-5, 6-2 win over Australia's Alex de Minaur.

Sinner (23) is the only top-10 man to make the semi-finals with number 12 Taylor Fritz due to face US compatriot Frances Tiafoe, ranked 20, in Friday's other last-four duel.

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Medvedev had to save 10 of 15 break points while his dream of making a 10th Slam semi-final was undermined by 57 unforced errors.

Sixth-ranked Pegula booked a place in the last-four of a Grand Slam for the first time by sweeping past Swiatek 6-2, 6-4.

On Thursday, she will tackle Karolina Muchova, who saw off Beatriz Haddad Maia of Brazil 6-1, 6-4.

Emma Navarro of the US tackles world number two and Australian Open champion Aryna Sabalenka in the other women's semi-final.

Draper pulled off the 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.

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

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Draper is the first British man to make the last four since Andy Murray won the title 12 years ago. He 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.

Draper sent down 11 aces among 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 record although that win at Queen's came three years ago.

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.

Before Wednesday, she had lost six times at the quarter-final stage at the majors.

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

Swiatek was undone by 41 unforced errors and was left to ponder an uneven season at the Grand Slams.

There was the high of a fourth French Open triumph, but that was sandwiched by third-round exits at the Australian Open and Wimbledon.

At the Paris Olympics, played on her favorite Roland Garros courts, she had to settle for the bronze medal.

"It's hard to have low expectations when everybody is expecting something from you," said Swiatek.

Muchova's win over 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. "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.