Juan Martin del Potro and Dominic Thiem have just headed out on court for their fourth-round clash.

We're done for the day, and so is Kaia Kanepi who has just beaten Daria Kasatkina 6-4 6-4 on Louis Armstrong Stadium.

Keep an eye on the website for reports on Del Po-Thiem and Roger Federer against Philipp Kohlschreiber later.

We'll be back tomorrow. Until then!

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Coco Vandeweghe speaking after her victory: "I was definitely happy to play mixed yesterday to get lactic acid out. Lucie serves very well and hits the ball cleanly off the baseline and I had to try and retrieve which isn't my forte.

"My grandfather said he was the best athlete in the family. I'm happy to have friends and family out here to push me forward as I'm trying to catch my grandfather.

"Hopefully we can make it four Americans left and Madison Keys can win tonight. It's a great section to be in. I love playing in quarter-finals so I can hopefully keep it going."

On playing Pliskova: "She plays a pretty big game. She holds serve very quickly and makes it difficult to get a rhythm. But she also has to worry about me. I do the same thing on my service game. Hopefully you guys will push me through again."

Pat Cash is waving to Vandeweghe on the court like an excitable child, which is unbelievably sweet. The two of them seem to have a really lovely relationship.

Up next for Coco Vandeweghe is world number one Karolina Pliskova.

Safarova back on serve.

She tries to poke the ball over the net from close range after a rally, but she can't clear it.

The pair switch ends, and on Safarova's second serve the Czech plonks the ball long over the baseline while doing the splits. Ouch.

Safarova flights her return to a big Vandeweghe serve wide to draw the two level again.

Then a nice skip to the net from the American allows her to move in front with a backhand winner.

One good, one bad.

Vandeweghe snatches a point back but can only play the next one wide.

Ooh. Vandeweghe aims down the line and ends up flicking it long.

Now then.

Forehand winners aplenty from Safarova, and she holds to love. Hello, tie-break.

Image source, Reuters

A wayward forehand is the only error from Vandeweghe as she skips through her service game.

It's down to Safarova to try and force a tie-break.

Clever stuff from Coco, sending Safarova this way and that before curving a backhand winner beyond her for 15-15.

The Czech then double faults - her third of the match - before a Vandeweghe backhand and a volley winner allow her to hold.

Dennis Ethan: Please can you tell me what tennis players are looking at when picking balls to serve with?

Superstition? Fluffiness? Greenness? I suspect it's a combination of all those things.

A fine forehand from Vandeweghe is the best shot of a speedy game as she holds to love.

Image source, Reuters

Kaia Kanepi is running away with her last 16 match against Daria Kasatkina.

The Estonian is 6-4 4-1 to the good over on Louis Armstrong Stadium.

Eurgh. Safarova is in complete control of the point, Vandeweghe has given up as the Czech moves in for a smash, there's acres of open court - and she plonks it down in front of her feet. Dearie me.

She still holds to 30, mind.

Long on the backhand from Safarova, crouching down low, and follows it up with a loopy forehand. Vandeweghe holds.

Image source, Getty Images

Vandeweghe ups her tempo to move to 40-30 after Safarova snaffles a couple of points.

That's deuce, though, as a forehand winner comes off Safarova's racquet.

Vandeweghe races to a 0-30 lead, courtesy of a stonking forehand winner, before Safarova cracks down an ace.

A loose backhand from Vandeweghe draws the two level, but then Safarova fluffs two backhands down the line to cancel out her break straight away.

Image source, Getty Images

Estonia's Kaia Kanepi has taken the first set 6-4 against Daria Kasatkina of Russia over on Louis Armstrong Stadium.

The winner will play either Elina Svitolina or Madison Keys in the quarter-finals.

Image source, Getty Images