As she has all tournament, Aryna Sabalenka is wearing a chunky gold necklace with coloured jewels in it as part of her outfit for this game. It's very Infinity Gauntlet coded, for any other Marvel nerds in the audience.

Anyway, Pegula has just held to love. Both women have been excellent on serve so far.

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There are a few latecomers into the arena, and the umpire calls out one spectator for not taking their seat as Sabalenka is about to serve. Given the focus on fan behaviour at this tournament, that may be one to keep an eye on.

Back on court, Jess Pegula continues to strike the ball superbly - she is up to four forehand winners already.

But Sabalenka responds with a 117mph ace, before holding to 30.

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Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

Sabalenka is looking very sharp.

I have always thought she loves to go after the ball. She has often said that she knows what she can do in practise and she will just implement it in a match. When the going gets tough in a match, she will back herself.

But Pegula is hammering that ball. She is on it and is seeing the ball very clearly. Her team is looking very intense down there, but they must be happy with how she is playing.

This is a good level of tennis from both of them.

Jess Pegula has a little bit of strapping on her right thigh. That's new, but she doesn't seem to have any obvious issue with movement so far.

And she holds as Sabalenka goes long.

The first sniff of a break in this match comes from Aryna Sabalenka, a dismissive return winner puts her 0-30 up.

Jess Pegula responds perfectly with the first ace of the match, then Sabalenka is left frustrated as a return flies wide. 30-30.

But as Pegula finds the net, it is break point Sabalenka...

A roar from the crowd as the American saves it with a fine forehand out wide. Deuce.

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Emily Salley
BBC Sport

"Oh, wow".

That was Coco Gauff's surprised reaction when she learned she was part of a US Open semi-final line-up the like of which has not been seen in more than half a century.

For the first time since 1975, the top four seeds in the women's singles draw have reached the semi-finals at the New York major.

Now, 51 years later, the stars have aligned once again with Aryna Sabalenka, Elena Rybakina, Jessica Pegula and Gauff all surviving three-set thrillers to create a semi-final line-up for the ages.

"How amazing - it doesn't get much better than that does it?" former British number one Annabel Croft said on BBC Radio 5 Live.

"It has felt fantastic the whole tournament - I just feel like I've been more enthused about looking forward to the match-ups this Grand Slam than any I can remember."

So far, this match is of the high quality we hoped.

Sabalenka goes a little wavy with her serve, missing her first effort on the opening three points. But she holds to 15, and we stay on serve into the first changeover.

As always, we would love to hear your thoughts on tonight's matches - whether you are staying up late in the UK, following Stateside or anywhere else in the world.

Click the 'Get Involved' tab and we will feature the best of your correspondence on this live page.

If Jessica Pegula is feeling under pressure given her poor Slam record against Sabalenka, she is not showing it.

Four first serves in, and a hold to love.

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Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

I think the four [semi-finalists] that we have got have been the best performers and the most consistent. They will produce some great tennis tonight and it will be very entertaining.

A smooth start for the top seed, as Sabalenka gets all her first serves in as she holds to 15.

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And away we go.

First point to Sabalenka as Pegula goes long at the net.

The players are out on court; Aryna Sabalenka was wearing a huge pair of headphones to block the noise of what will be a boisterous and partisan New York crowd.

An early boost for Sabalenka as she wins the coin toss, and chooses to serve first.

Image source, Getty Images

Image source, Getty Images

Jessica Pegula is the only player remaining in the women's draw still chasing a maiden Grand Slam.

She needs no introduction to opponent Aryna Sabalenka - they have faced each other 13 times.

That includes the past two US Open tournaments, when Sabalenka denied Pegula a first major title in the 2024 final and fought back to win in last year's semi-finals.

"It's fun to look at it like a rivalry. I think that's what motivates me," said Pegula.

"I know that she's definitely pushed me to become a better player, so I always respect and appreciate that aspect of our rivalry."

Pegula, who has got the better of Sabalenka on four occasions on the WTA Tour, said beating the four-time major winner at Grand Slam level is a "hurdle" she must overcome.

Elizabeth Botcherby
BBC Sport

Jessica Pegula's frustration was clear as she grappled with 26th seed Emma Navarro and her own inconsistency, before eventually plotting her way to a third consecutive semi-final at her home slam with a 3-6 6-4 6-3 win in the quarter-finals.

Finishing as runner-up in New York to Sabalenka two years ago remains the closest the 32-year-old has come to capturing a major title.

The American number one roared with relief after withstanding the last of 24 break points to serve out victory after two hours and 21 minutes.

"I was fighting a lot of demons out there today," Pegula told the crowd.

But no WTA player has claimed as many comeback wins (48) and three-set wins (90) since the start of the decade, which will only boost her belief.

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World number one - for now - Aryna Sabalenka is aiming to become the first woman since Serena Williams in 2014 to win the US Open women's singles title three years in a row.

Sabalenka was in shaky form heading into this tournament and will lose her top ranking to Elena Rybakina after the tournament, as the Kazakh also reached the semi-finals to accrue the points required to overhaul her.

But Sabalenka has fought her way to the semis, and knows what is needed to get the job done from this moment onwards.

Elizabeth Botcherby
BBC Sport

Aryna Sabalenka thought she had lost her US Open crown before leaving herself "speechless" as she battled back to beat Linda Noskova in three sets and advance to the semi-finals.

Taken to a deciding set for the first time in this year's tournament, the two-time defending champion trailed 4-2 in the third set and later 2-0 in the tie-break before recovering to close out a 7-6 (7-1) 3-6 7-6 (10-7) win.

It was the 28-year-old's 19th consecutive win at the tournament, having not tasted defeat since the 2023 final, while she becomes the first woman since Serena Williams in 2016 to reach six successive semi-finals at Flushing Meadows.

Image source, Getty Images