Williams beats Kvitova 6-3 3-6 7-6 (7-2) to reach semi-finals
Roof closed during second set on Arthur Ashe Stadium
Stephens beats Sevastova 6-3 3-6 7-6 (7-4) to make last four
Carreno Busta beats Schwartzman 6-4 6-4 6-2 to make men's semis
Stephens 5-2 *Sevastova
Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows
We have seen Sloane Stephens have the upper end on those drop shots.
She's started running in before Sevastova even hits them - I think that is intimidating her a little.
Stephens is so deceivingly quick.
Stephens 5-2 *Sevastova
Well, as Crispin Mills sang in the mid-90s this match is a "freaky roller coaster ride".
Two breaks points for Anastasija Sevastova go begging as Sloane Stephens flirts with danger on serve once again but veers away from the precipice and takes the game.
The scoreboard makes it look like this is a cakewalk for Stephens, but this match is as funky as a discarded Kula Shaker b-side.
Stephanie Siu: After watching Jamie and Bruno (lose) on Grandstand earlier, we're now back on Ashe and not as stressed about who wins!
*Stephens 4-2 Sevastova
Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows
It's really elegant form from Sevastova - great technique, light on her feet.
She doesn't really have that fourth or fifth gear, that's why she gets pigeon-holed in the early rounds and loses out to a big-hitter.
Image source, AFP*Stephens 4-2 Sevastova
Thirty-all on your own service is not the platform for breaking out your Albert Hall exhibition trick shots.
Anastasija Sevastova's chop forehand drop-shot from way behind the baseline is swallowed by the net and suddenly her serve is an endangered species.
Break point.
Sevastova goes back to a winning formula, channeling some forehand fire on the American.
Break point saved. Game salvaged. And the set, still, just about, in the balance.
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Three days after her US Open ended, Maria Sharapova is back at it in the gym...
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Stephens 4-1 *Sevastova
Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows
Sloane Stephens is playing well within herself since that first game.
She started slowing down between points in this game and that can get to you in these big moments.
It's just one shot here or there, that tells you how close the match is.
Stephens 4-1 *Sevastova
After losing the first four points of the match, the Flushing Meadows crowd find their woman in firm control.
She knuckled down and batted back Sevastova's challenge.
Image source, Reuters*Stephens 3-1 Sevastova
Down break point, Sloane Stephens dares to dare, hitting out to win the point rather than plonking back into court and hoping her opponent breaks down.
Deuce.
*Stephens 3-1 Sevastova
Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows
If looks could kill... Sevastova is looking up at her box like something is really wrong here.
She's jerking her head up in the middle of the swing and that creates errors.
Image source, Getty Images*Stephens 3-1 Sevastova
That ball is off out of Queen's, heading to Manhattan and catching a ferry to New Jersey.
Sloane Stephens absolutely splatters a mid-court volley away to seal a successive break to open up some clear blue water on the scoreboard.
Stephens 2-1 *Sevastova
Anastasija Sevastova dredges deep and drags two break points off the table.
The Latvian is not out of the woods yet though. She is back to deuce.
Image source, Getty ImagesStephens 2-1 *Sevastova
Sloane Stephens has another chink to try and prise into a break at 0-30 up.
A forehand that sits up and begs for her to clobber cross-court ends in the net.
A shake of the American's head. But that is better!
A foxy little drop-shot reply brings up 15-40 and two break points.
Image source, ReutersStephens 2-1 *Sevastova
Sloane Stephens tastes the fresh air of being in front on the scoreboard for the first time.
Image source, AFP*Stephens 1-1 Sevastova
Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows
Anastasija Sevastova is getting fired up, yelling at her coaching box.
Both ladies play with good pace in between points, we won't be needing that shot clock.
Image source, Getty Images
Piers Newbery
BBC Sport at Flushing Meadows
It's that sort of afternoon in New York, one for finding a patch of grass and crashing out. The hottest temperatures of the tournament are expected over the next few hours as it nudges 30C, so it will be hotter and hard work down on the Arthur Ashe court.
Save your jealousy though, tomorrow will be a day of relentless rain apparently.
Image source, BBC Sport*Stephens 1-1 Sevastova
And the American levels up the match. A break apiece and no closer to finding out whowunit?
Stephens 0-1 *Sevastova
Anastasija Sevastova is sporting a dress that seems to be designed around the 'snow' you see on an de-tuned telly.
Nicely disguised dropper from the Latvian, but Sloane Stephens runs it down, dinks a cute reply before bulleting a ball straight towards the 16th seed's neck.
30-all.
And now we are into deuce street as Sevastova double faults...
Stephens 0-1 Sevastova*
Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows
Sloane Stephens was extremely aggressive on the first point, but has now become way too defensive.
She looked down and shook her head like she had been sent to her room.
You have to shake it off, look at it as an opportunity and not 'what big prize money, what points I can get' - bring it back to one point at a time.
Stephens 0-1 *Sevastova
Sloane Stephens misses a routine drive volley off the first point with Anastasija Sevastova not even on the scene.
And from there it gets worse. Fast.
Too defensive, too timid.
And Sevastova shows no such second thoughts as she claims the first break point from 0-40 up.