Some brilliant defensive play from Karolina Muchova but, ultimately, it is not enough to stop a relentless Naomi Osaka, who is striking the ball immaculately.

Muchova responds with a fantastic return down the line for a winner but Osaka just keeps going and hammers a forehand deep into the corner to hold.

Now then, is Alexander Zverev blinking first?

He's taken to deuce - but responds with a cracking ace out wide well out of Jiri Lehecka's reach.

Can't follow it up immediately, sending a backhand long - but two more brilliant serves, one out wide and one down the middle, both unreturnable, quell the danger. A hold but hard-earned.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Live

Once Osaka gets into it and gets going, she is near impossible to stop. She just hasn't been able to get into the game of Muchova yet.

Annabel Croft
Former British number one on BBC Radio 5 Live

I think already Muchova is playing at a level that can definitely win this match. But, it's whether or not she can hold it when she has to.

Naomi Osaka is rattled because she hasn't played anyone like this.

Top seeds Henry Patten and Harri Heliovaara will have to come through a first-to-10 tie-break on court two to reach the men's doubles semi-finals.

You can watch the conclusion of that match on the BBC iPlayer.

A blink-and-you'll-miss-it service game from Karolina Muchova.

An excellent serve out wide can't be returned by Naomi Osaka and the Czech 10th seed holds to love.

Harry Poole
BBC Sport at Wimbledon

And I thought Coco Gauff against Jessica Pegula was topsy-turvy!

It’s got nothing on the start to this match.

Four breaks of serve, a first hold of serve from Karolina Muchova, and now Naomi Osaka overcomes a break point to bring us level again.

You certainly can’t call it after the opening 25 minutes.

Todd Woodbridge
Former Wimbledon doubles champion on BBC One

Jiri Lehecka is physically strong and has power off both wings, but there are times where he doesn't show finesse. For me, that would be the one thing he could add into his game to enhance it.

For example, I like a sliced backhand to bring in an opponent and change the pace of a rally - and he doesn't seem to do that often enough.

He is also the sort of player that feeds off confidence. If he is feeling good, he plays big. But he isn't as good at winning matches when he isn't at his best. That's the consistency he is trying to develop.

Image source, PA Media

Regina in Reigate asked this question yesterday during Alexander Zverev's fourth-round match against Jiri Lehecka:

I'm a bit confused - I'm sure I saw Zverev using a mobile device during a changeover of ends... now I don't know exactly what he was looking at, but I thought all mobile devices were not allowed during a game.

Zverev has Type 1 diabetes and has a glucose monitor in his bag which he regularly checks. It helps regulate his glucose levels and tells him if he needs to inject any insulin.

He recently said the monitor malfunctioned during his match in Halle and he injected more than he needed., external

Players are not allowed to check their mobile phones during a match.

Annabel Croft
Former British number one on BBC Radio 5 Live

I think there's not many players who come close to the way Muchova plays tennis and the construction of her points. She's incredible to watch.

You won't see a better serve and volley than hers.

Just brilliant from Karolina Muchova.

From 0-30 she gets another break point, producing a brilliant drop shot and then works Naomi Osaka one way then the other on the next point, winning it with a push volley into the corner.

But Osaka had only been broken three times in the tournament before today for a reason and pulls out two big serves to get out of trouble before securing her first hold.

Jiri Lehecka needed a replacement banana at the change of ends because the one he had ready was, well, it seems, too hot to eat.

An indication of the roasting conditions these players are playing in. A ball girl comes to the rescue with a fresh, cooler, replacement.

Once again, the Czech's serve is similarly too hot to handle for Alexander Zverev - and even when the second seed can extend a couple of rallies, he errs into the net.

A cracking forehand around the net post seals a hold to 15.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Live

I have a tennis crush on Muchova, she's the best player to watch. I love watching her play.

Annabel Croft
Former British number one on BBC Radio 5 Live

Muchova walks so carefully around the court, it's like she's trying not to stand on some daisies on the grass or something. Very careful placement of the feet.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 Live

These two players have the best service technique in the game. The technique is just perfect.

A hold at last!

Karolina Muchova gets this one done without any issues. A hold to 15.

Image source, PA Media

Serve dominating on Centre. Since Alexander Zverev's wobble at the end of the third set, neither player has had a sniff of a break point.

That continues as the German holds to 15, a series of superb serves meaning he barely needed to break sweat in any rallies.

Image source, Getty Images

An ace out wide followed by a scorching forehand that just kisses the line get Naomi Osaka off to the perfect start in her second service game.

But two errant backhands, one thumped long and the next into the net, get Karolina Muchova right back into it.

It gets to deuce before Osaka overcooks another booming forehand and Muchova has another break chance.

Taken! Another backhand into the net from Osaka and it's four breaks to start the match.

Henry Patten and Harri Heliovaara are heading towards a tie-break in the deciding set against Guido Andreozzi and Manuel Guinard.

The third set of the men's doubles quarter-final is going with serve, with neither pair earning a break point.

Jiri Lehecka giving second seed Alexander Zverev plenty of food for thought.

A crunching ace down the middle of the service box seals a hold to 15. The Czech has won 16 of 18 service points since today's resumption.