US Open day nine - listen to BBC Radio 5 Live commentary (UK only)
Two-time winner Naomi Osaka plays second seed Elena Rybakina (not before 20:30 BST)
Rybakina will replace Aryna Sabalenka as world number one if she reaches last four
Six-time major champion Iga Swiatek beaten 7-5 6-3 by Olympic champion Zheng Qinwen
Swiatek has not got past last eight in New York since winning title in 2022
French Open champion Mirra Andreeva recovers from losing first set to defeat Anastasia Potapova and reach quarter-finals
We're going to park our live text coverage for now but we'll be back later for two-time US Open champion Naomi Osaka's fourth-round match against second seed Elena Rybakina.
That match is third on Louis Armstrong Stadium and due to start after the women's doubles match between Katerina Sinakova and Taylor Townsend, and Storm Hunter and Desirae Krawczyk, which has just got under way.
See you soon!
Swiatek 5-7 3-6 Zheng
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
Wow. Zheng just doing the incredible magic. She has already done so much in her career but this must be one of her most special victories given where she has come from. It is like an Emma Raducanu fairytale right there.
Swiatek 5-7 3-6 Zheng
Image source, ReutersZheng Qinwen speaking on court after beating Iga Swiatek: "I have to say I started the match not so well but after I found my rhythm on the centre court - because it has been a long time since I have played here. I just really appreciate being here.
"I focused point by point and little by little, I played better tennis and I started to find my game. At one moment, I even forget the score, that shows my focus.
"I think the baseline I tried to play more flat against her because she has a really good topspin and she makes me feel uncomfortable. I tried to play more aggressive. I am really happy to win this match because it was not easy.
"The more matches I play, the more rhythm I get. I just feel really pumped and ready for my next match."
Andreeva 5-7 6-4 6-3 Potapova
Mirra Andreeva speaking on court after beating Anastasia Potapova: "She is my good friend and seeing what a battle we had, then seeing her fall is not easy. I can't imagine what she's going through.
"It's not the way you want to finish the match but I just told her that she's been playing amazing and that I'm sure she'll come back even stronger. She's a warrior.
"I'm super happy that I was able to find motivation inside myself to fight. It was not easy, I didn't really know what to do to beat her in the first set because she had answers to everything I was playing.
"Happy to win but still pretty sad with how it ended."
Swiatek 5-7 3-6 Zheng
Image source, ReutersA fourth match point for Zheng Qinwen and she makes this one count as Iga Swiatek goes into thed net.
Zheng drops her racquet and falls flat out on her back on court in celebration.
She then acknowledges each section of the crowd, who are rightly giving props to that magnificent performance.
Zheng was 5-0 down in the first set before that remarkable comeback.
*Swiatek 5-7 3-5 Zheng
A couple of wayward shots from Iga Swiatek put her in trouble, before the Pole goes long with a forehand to offer three match points to Zheng Qinwen.
Swiatek recovers brilliantly though to force deuce, the pick of the points being a superb forehand winner down the line.
Andreeva 5-7 6-4 6-3 Potapova
Image source, Getty ImagesMirra Andreeva is through to the US Open quarter-finals for the first time.
She wasn't quite at her best but she comes back from a set down and gets the job done.
It's a sad end for Anastasia Potapova, who came back on court with heavy strapping just above her left knee and was struggling badly.
Andreeva wins the three points she needs but there's no big celebration, she just walks around the net to give her opponent a hug.
*Swiatek 5-7 3-5 Zheng
Zheng Qinwen is playing really well now and a couple of unplayable serves puts her in control of the game.
She wraps it up in style, stepping inside the court to put away a backhand winner across the court.
The crowd roar and Zheng is one game away from the quarter-finals.
Swiatek 5-7 3-4 Zheng*
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
What is most impressive is the reaction after just breaking Iga. She is so composed and so dialled in. She is not wasting energy on anything else, which is very different from what we are seeing on the other courts.
Swiatek 5-7 3-4 Zheng*
Image source, Getty ImagesA bit of pressure on Iga Swiatek here as she finds herself 30-30.
Swiatek is fuming as she goes wide with a forehand to offer break point, and Zheng Qinwen makes it count in style with a return winner which leaves the Polish eighth seed stranded.
Zheng clenches her fist in celebration before the change of ends.
*Andreeva 5-7 6-4 5-3 Potapova
Image source, ReutersWith Mirra Andreeva just three points from victory, we've got an injury delay.
Anastasia Potapova goes down after playing a forehand down the line and seems to have an issue with her knee.
Andreeva goes down to check on her, helping her to her feet and gesturing for the physio.
It's 0-15 on the Potapova serve, she'll want to get back on court to finish the match but first she is going to need some treatment.
*Swiatek 5-7 3-3 Zheng
Image source, Getty ImagesZheng Qinwen gains advantage with an ace before Iga Swiatek guides a backhand winner down the line for deuce again.
Zheng steps up with a backhand winner of her own, before Swiatek goes into the net.
There's not much between these two at the moment.
Swiatek 5-7 3-2 Zheng*
A lengthy rally ends as Zheng Qinwen plants a forehand into the net.
Iga Swiatek then forces her into a mistake, before a wild forehand gifts two break points to the Polish eighth seed.
Swiatek goes for broke with a powerful forehand but it finds the net, before letting the second break point slip away with another forehand which goes wide.
*Andreeva 5-7 6-4 4-3 Potapova
Image source, Getty ImagesAnastasia Potapova finds herself down 15-40 on serve - a point away from Mirra Andreeva serving for the match - but she comes out fighting.
A superb drop shot saves the first before a pulsating point ends with another, this one hits the net chord and drops... just on Andreeva's side.
No chance for the fifth seed and Potapova keeps it to just the one break defecit.
Swiatek 5-7 3-2 Zheng*
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
It has been a while since Swiatek has been able to dictate and finish off with a winner. For the last hour, she has been on the back foot and is struggling to keep up with the pace.
Swiatek 5-7 3-2 Zheng*
Image source, Getty ImagesZheng Qinwen opens up the game with a brilliant forehand return winner, bringing oohs from the crowd.
Iga Swiatek is frustrated with herself as she puts a forehand long, but recovers well to level at 30-30.
Swiatek has to save a break point to take the game to deuce, but moves up a gear to secure the hold as Zheng can't keep a forehand in play.
*Swiatek 5-7 2-2 Zheng
We're back under way on Arthur Ashe Stadium and Zheng Qinwen gets right back to work with a glorious forehand winner past Iga Swiatek, who had come in to the net.
The Chinese world number 121 wraps up the game as Swiatek drags a forehand wide.
*Andreeva 5-7 6-4 3-2 Potapova
Mirra Andreeva secures the first hold of the third set - just.
It's very nearly a fourth break on the trot after two double-faults from the 19-year-old.
But she stands firm, gets back to deuce and is then helped by a couple of loose forehands from Anastasia Potapova.
The 24th seed digs in from 15-30 to secure a hold of her own but Andreeva remains a break up.
Swiatek 5-7 2-1 Zheng*
Image source, ReutersThe physio is working on Iga Swiatek's thigh so I can only assume that's where the problem is.
Hopefully the issue is not serious enough to affect her performance.
You get three minutes for a medical timeout but Swiatek ran on court with 40 seconds remaining, so that's positive.
*Andreeva 5-7 6-4 2-1 Potapova
Image source, ReutersSuperb from Mirra Andreeva and she quickly regains the advantage in the third set.
Having brought up break point, the French Open champion is right up against it with Anastasia Potapova throwing everything at her.
But Andreeva's defence is rock solid, she stays in the point and eventually Potapova plinks a forehand into the net.
