Sloane Stephens is in the mire once again.

Anastasija Sevastova caresses a dreamboat of a drop-shot over the wire to set up break point from deuce.

That was delicious.

Sloane Stephens knocks her back from that chance.

Back to 40-40.

A side order of shade?

Don't mind if we do.

Sloane Stephens clumps a smash straight at Anastasija Sevastova in reply to the Latvian's drop-shot.

It catches Sevastova right on the leg and the 17th seed takes the proffered hand of apology with a raised eyebrow.

Sevastova holds though and is making the second-set pace.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

In this very tight match, at this point, it's interesting to note Sloane Stephens has had about twice as much prize money as Anastasija Sevastova, even though they've played for a similar amount of time.

Anastaija Sevastova's tenacity pays dividends.

A titanic point of to and fro, back and forth, ends with Sloane Stephens' attacking athleticism finally running down Sevastova's determined defences.

That is 15-15.

But Sevastova tickles over a feather-duster of a drop-shot to bring up break point.

And Stephens cuffs the double-handed backhand punch wide!

Image source, Rex Features

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Stephens is investing a lot of physicality into these points because she feels like she can pull away in this match.

It might be a chance for Sevastova to make it an endurance match, if she can suck Sloane into every point.

Stephens has played it safe and it's one of those curses of decision making, there are some times when you have to bring the heat.

I would tell her to play her margins, use more angles, but if that ball is hanging around in the middle of the court then knock the cover off it.

Anastasija Sevastova clings onto her serve by her fingernails. Sloane Stephens is straining at the leash to take this set - and the match - over the horizon and out of reach.

But the Latvian - who beat Maria Sharapova in three sets in the last round - is still hanging about to try and trigger the gremlins upstairs for Stephens.

Gigi Salmon
BBC Radio 5 live sports extra commentator at Flushing Meadows

Image source, BBC Sport

The new 14,000-seater Louis Armstrong Stadium is slowly taking shape - it will be ready for next year's tournament.

And it will have a retractable roof too so the US Open will have two covered courts available for rain delays.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Sevastova looks exhausted, mentally and physically.

She's very flat-footed, almost on the back of her heels, looking up at her coaching box with almost every loss of point.

Anastasija Sevastova fluffs a horrible drop-shot towards the net, the ball bouncing miserably before shame-facedly burrowing into the gauze.

Sloane Stephens shows her how it is done with a touch as smooth and delicate as gossamer.

Sevastova looks like she is fading. There was not much of a challenge to that Stephens service game.

Image source, EPA

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

To give credit to Sloane Stephens' coach, when he first came on the scene I was saying 'what could this guy really do for her?'

She was such a great talent already, but he's really put something between her ears, I think.

Sloane Stephens is walloping the ball as clean as a whistle and as fresh as a thistle.

30-all as she stretches Anastasija Sevastova out of shape.

That is really smart hold from a sticky spot for the Latvian though.

A backhand bosh down the line for a winner is followed by Stephens prodding long.

Image source, EPA

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Sloane Stephens played well, very few unforced errors - 13 - I've seen her make 30/35 in a set.

That first serve in play and those few unforced errors makes life pretty easy.

That keeps the pressure on Sevastova and she never got a chance to get into a rhythm.

Gigi Salmon
BBC Radio 5 live sports extra commentator at Flushing Meadows

Image source, BBC Sport

Here's John McEnroe in the ESPN studio with a Rafael Nadal impersonator. It's unclear whether the people watching are aware that's not the real Rafa.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Sloane Stephens seems like she has so much time in between shots and she's just in a hitting session.

Oooh!

Sloane Stephens looks vulnerable at the net at 0-15 down but Anastasija Sevastova drifts her forehand wide down the line with a large chunk of court to aim at.

Sevastova blots her backhand long to offer up two set points at 40-15.

Stephens chows down on an all-you-can-eat midcourt fend and that is the set done and dusted.

Image source, Getty Images

Anastasija Sevastova keeps her cards on the table after seeing off Sloane Stephens from deuce.

With Anastasija Sevastova looking a little tentative, we are back up and running.

The Latvian serves to stay in the opening set next...

That match Stephanie was referring to (20.22 entry) saw the end of Jamie Murray and Bruno Soares' defence of their US Open men's doubles title, as they were heavily beaten by Jean-Julien Rojer and Horia Tecau in the quarter-finals.

The British-Brazilian fourth seeds lost 6-1 6-2 in only 62 minutes.

Murray plays alongside Martina Hingis in the mixed doubles last eight later, against Abigail Spears and Juan Sebastian Cabal.

Image source, Rex Features

Actors Dave and James Franco seem to be enjoying Stephens's performance so far.

You wouldn't get away with putting your feet up on furniture in the Royal Box.

But you probably don't get a big box of chocolates doing the rounds in New York.

Swings, roundabouts.

Image source, Getty Images

Anastasija Sevastova calls for the trainer, lays out the towels and proffers up a leg to the medic.

It seems the problems is around the side of her knee.

A grimace from the Latvian as the medic's digits dig into the joint.

Image source, Reuters