US Open day seven - listen to BBC Radio 5 Sports Extra commentary (UK only)
LIVE: Two-time defending champion Aryna Sabalenka faces home favourite Taylor Townsend
"The outfit is quite something" - Townsend walks out wearing feathery hood
Sabalenka must win title - and hope Elena Rybakina loses before semi-finals - to keep world number one ranking
Followed by: Carlos Alcaraz against American Tommy Paul
Second seed Alcaraz bidding for third New York title and eighth major overall
Wimbledon champion Linda Noskova faces Marta Kostyuk in rematch of SW19 semi-final
Sabalenka 5-3 Townsend*
Aryna Sabalenka miscues a forehand into the net and is broken to love.
If - and it's a big if - Taylor Townsend can hold serve now, the pressure will be back on the Belarusian.
Townsend is zero for four on her own serve so far in this match, though.
*Sabalenka 5-2 Townsend
Guess what? Taylor Townsend has three more break points to at least extend this first set.
*Sabalenka 5-2 Townsend
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live
I'm thinking if Townsend loses this set, she might take advantage of the one bathroom break you're allowed. Right now she's looking like she needs a couple of minutes to reset, she's taking a couple of deep breaths.
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*Sabalenka 5-2 Townsend
Oh, too good.
What a forehand winner from Aryna Sabalenka, who has a double break now and will serve for the opening set after the changeover.
Sabalenka 4-2 Townsend*
The crowd start a ripple of encouraging applause for Taylor Townsend as she sends her effort wide in the first point of her latest service game, perhaps sensing that the momentum is starting to move against her a little bit.
A couple of unforced errors later in the game bring up two more break points for Aryna Sabalenka.
Sabalenka 4-2 Townsend*
Image source, Getty ImagesFinally - a hold of serve!
Aryna Sabalenka races through the game, too, to take a 4-2 lead in the opening set.
*Sabalenka 3-2 Townsend
Image source, Getty ImagesTaylor Townsend whips a forehand down the line just wide on break point down and Aryna Sabalenka has a third break in the first set.
Will the world number one make this one count?
Neither player has held serve in this match yet.
Sabalenka 2-2 Townsend*
Aryna Sabalenka looks very non-plussed as she fails to lay a racquet on a return.
Her anger at that is put into the next point as she powers away a winner.
Then Taylor Townsend sends an overhead smash long, having done all the hard work in the point, and she's facing another break point.
Patten/Heliovaara 7-5 2-1 Arnaldi/Struff*
Image source, Getty ImagesGreat Britain's Henry Patten and Finnish team-mate Harri Heliovaara have taken the opening set in their second-round meeting with Italy's Matteo Arnaldi and German Jan-Lennard Struff.
The world number ones Patten and Heliovaara came through their opener in straight sets and will be hoping to do the same here.
The pair triumphed at Wimbledon this summer and are chasing their fourth major doubles title together - but first in New York.
Sabalenka 2-2 Townsend*
Image source, ReutersMake that four breaks of serve in a row to start this match.
Taylor Townsend climbs all over a return and her home supporters roar when Aryna Sabalenka's forehand finds the net.
*Sabalenka 2-1 Townsend
Goodness me... Aryna Sabalenka throws in a double fault and sends a volley wide, and suddenly she is facing three break points.
Image source, Reuters*Sabalenka 2-1 Townsend
Aryna Sabalenka has not lost a singles match at the US Open since her defeat by Coco Gauff in the 2023 final.
She has won 16 matches in a row at the event since then - 17 if you include the walkover against Marketa Vondrousova in last year's quarter-final.
*Sabalenka 2-1 Townsend
The first break point is saved but the second goes Aryna Sabalenka's way as Taylor Townsend's forehand drifts a few inches long.
Three breaks of serve to start this fourth-round match.
Sabalenka 1-1 Townsend*
Now Aryna Sabalenka has two break points, her power-hitting bringing success.
Sabalenka 1-1 Townsend*
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live
What a fascinating start. Two very aggressive servers on the court. Both broken in their opening service game, that's understandable. This court you have a special feeling, the nerves are tingling when you walk out, let's see now if the server can settle in.
Sabalenka 1-1 Townsend*
A double fault on break point by Aryna Sabalenka, who gives the break of serve straight back at the start of the first set.
Image source, Reuters*Sabalenka 1-0 Townsend
Image source, ReutersFar from being downhearted at losing her opening service game, Taylor Townsend finds two superb winners to move 0-30 up.
The American nets a return on the next point, but then brings up two break-back points as Aryna Sabalenka goes long.
*Sabalenka 1-0 Townsend
Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live
A 94pmh second serve that did handcuff Sabalenka, and that was a forehand that Townsend should have made.
Lots of times in a match, early games are so important. I feel like this one is super important.
*Sabalenka 1-0 Townsend
At the fifth time of asking, Aryna Sabalenka breaks Taylor Townsend's opening service game.
Townsend gets to Sabalenka's powerful cross-court backhand but sends her groundstroke long.
Sabalenka 0-0 Townsend*
An eventful opening game continues as Taylor Townsend finds a service winner to save a fourth break point.
