US Open day nine - listen to BBC Radio 5 Live commentary (UK only)
LIVE: Six-time major champion Iga Swiatek faces Olympic gold medallist Zheng Qinwen for place in quarter-finals
Swiatek has not got past last eight in New York since winning title in 2022
LIVE: French Open champion Mirra Andreeva loses first set 7-5 to Anastasia Potapova
Two-time winner Naomi Osaka plays second seed Elena Rybakina
Rybakina will replace Aryna Sabalenka as world number one if she reaches last four
Swiatek 5-4 Zheng*
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
Zheng's team are on their feet now, they know that she has what it takes to come back in this first set and the crowd know too.
She is doing such a great job of putting Swiatek under pressure.
Swiatek 5-4 Zheng*
Image source, Getty ImagesFrom 5-0 down to 5-4!
Zheng Qinwen breaks back again as Iga Swiatek can't keep her shot in play.
I did not see this coming around 10 minutes ago.
*Swiatek 5-3 Zheng
A groan of frustration from Iga Swiatek as a wide backhand gives Zheng Qinwen break point but she can't convert it as a forehand goes long.
Swiatek then skews a forehand down the line wide and the Chinese world number 121 has another chance to break.
*Swiatek 5-3 Zheng
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
Swiatek hit the net there. It was almost like she she didn't know how to get ready for the volley, that is how uncomfortable she feels around the net.
She is looking very stressed.
*Swiatek 5-3 Zheng
Zheng Qinwen got one break back on Iga Swiatek's last service game - can she do it again?
There's nothing Zheng can do about that as Swiatek's forehand across court finds the line, before the Pole brings up a third set point.
Zheng just won't go away though, as a rasping forehand takes the game to deuce.
*Swiatek 5-3 Zheng
Zheng Qinwen is making a match of this now.
She's started to get a foothold in the rallies to cause Iga Swiatek some problems, and she wraps up the game as the Pole can't get a forehand over the net.
Andreeva 5-7 2-2 Potapova*
Anastasia Potapova wasn't behind for long in the second set - she has broken back against Mirra Andreeva to level it at 2-2.
Swiatek 5-2 Zheng*
Image source, EPAZheng Qinwen earns another break point but Iga Swiatek snuffs it out with a superb backhand winner down the line.
The Pole just can't get over the line here as a long forehand gifts a third break point of the game to Zheng, and this time she makes it count as Swiatek goes long again.
That's one back for the Chinese world number 121.
*Swiatek 5-1 Zheng
Back to deuce as Iga Swiatek wins a rally, before the Polish eighth seed brings set point.
Zheng Qinwen saves it as Swiatek goes wide with a backhand.
*Swiatek 5-1 Zheng
The crowd are doing their best to give Zheng Qinwen a boost by cheering extra loudly when she wins a point.
This is the best she's done on Swiatek's serve so far as the game heads to deuce and she brings up break point as the Pole finds the net.
The volume level on Arthur Ashe Stadium goes up that little bit more...
Andreeva 5-7 2-0 Potapova*
Image source, Getty ImagesMirra Andreeva still looks a bit frustrated but she has made a positive start to set two after losing the first set to Anastasia Potapova.
The Russian teenager broke Potapova in the opening game and then escaped from deuce to hold serve for a 2-0 lead.
Swiatek 5-1 Zheng*
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
Even though she is 5-1 down, I have to say I'm liking what Zheng is trying to do in the rallies.
If Iga Swiatek drops her intensity even a little bit, as we're seeing right now, this match has the potential to go the distance.
Zheng has the groundstrokes to overpower Iga.
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
There has been a lot of excitement. The women's field in particular, it's in such a healthy, strong position.
It's one of those tournaments where anyone can take it from here.
*Swiatek 5-1 Zheng*
Image source, ReutersThat will do Zheng Qinwen's confidence a world of good as she finally gets on the board.
She wraps the game with with a lovely backhand volley which Swiatek can't reach in time as she sprints in towards the net.
Swiatek will now serve for the first set.
Swiatek 5-0 Zheng*
Iga Swiatek is well on top so far but a large part of it is down to Zheng Qinwen's unforced errors.
She's hit eight so far to Swiatek's two.
On serve, the Polish eighth seed sees out a comfortable hold to love and she's now one game away from the first set.
*Swiatek 4-0 Zheng
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
It seems like the fatigue is starting to kick in for Zheng, unfortunately.
The adrenaline will have been pumping after that comeback win in the last round but she just can't seem to get the tiredness out of her legs.
*Swiatek 4-0 Zheng
Zheng Qinwen's underwhelming start continues as she offers Iga Swiatek another break point before a double fault sees the Polish eighth seed win the game.
Andreeva 5-7 0-0 Potapova*
Image source, Getty ImagesAnastasia Potapova lets out a huge roar as she takes the first set of her fourth-round match against Mirra Andreeva on Louis Armstrong Stadium.
It looked to be heading for a tie-break, but Andreeva's frustration was starting to grow in the closing moments of the opening set and she was broken to love by Potapova.
Andreeva, the French Open champion, would be the highest seed to exit the women's draw so far if she is beaten today.
Swiatek 3-0 Zheng*
Zheng Qinwen works Iga Swiatek around before stepping inside the court to put away a forehand winner.
She's still making too many unforced errors however, and a couple more loose forehands bring up two break points for Swiatek.
Zheng fights back well, with Swiatek unable to take advantage of a second serve, and the game heads to deuce.
Swiatek 3-0 Zheng*
Daniela Hantuchova
Former world number five on BBC Radio 5 Sports Extra
I think Iga Swiatek is enjoying that not too many of us picked her as a favourite coming into the tournament.
