Jiri Lehecka finally loses a point on serve this afternoon...

Doesn't really matter, though, as the 24-year-old Czech was already 40-0 up when Alexander Zverev hit a tidy forehand winner.

Undeterred, Lehecka keeps booming down the big hits to force another Zverev error to wrap the hold of serve up.

Well then! That's a very impressive response from Karolina Muchova!

She breaks back immediately, helped by a double-fault from Naomi Osaka and then a very loose backhand that sails long.

Just the third time Osaka has been broken this year at Wimbledon and we're back on serve.

A real mix of a service game from Alexander Zverev - a couple of dominant points to go 30-0 up but some pretty unexpected unforced errors to let Jiri Lehecka back in to deuce.

He's nowhere near as clinical as he was when this game began last night - is the rising temperature on court affecting him?

Well, a booming serve down the middle followed by another out wide suggest not. Maybe he just needed time to settle - first game on the board for Zverev upon the resumption of this delayed fourth-round tie.

Strong start from Naomi Osaka and she quickly brings up two break points.

Early pressure on Karolina Muchova... and it tells.

A weak forehand into the net from the Czech and Osaka - who is hitting the ball crisply - has the advantage.

It's three wins apiece in the six previous meetings between these two.

Naomi Osaka has won the two most recent in Grand Slams but had to retire injured when they played just 10 days ago in the Hamburg final.

Here come the players on Court One.

Not quite the full kimono for Naomi Osaka today, a slightly - and I stress slightly - more low-key outfit for the four-time major winner.

Karolina Muchova wins the toss and elects to serve first.

Henry Patten and Harri Heliovaara have taken their men's doubles quarter-final into a deciding set - you can watch the conclusion on the BBC iPlayer.

Three games played. Alexander Zverev, the second seed, won one point.

Unreal from Jiri Lehecka.

A second successive hold of serve to love for the Czech, sealed by an ace down the T. That curfew last night looks to have done the 13th seed the world of good.

Goodness, Jiri Lehecka has come out firing.

Rocket returns from the Czech set up a 0-30 advantage and more than a sniff of a break.

Alexander Zverev replies by getting the best of a big-hitting rally - but Lehecka responds in kind on a similarly aggressive point for 15-40.

And Zverev can only send another fine return into the net. What a start from Lehecka!

Image source, Getty Images

Naomi Osaka has never played better on grass and having ousted world number one Aryna Sabalenka in the fourth round, she will surely believe she can beat anyone right now.

Having never previously got past the third round at SW19, Osaka's impressive win over Sabalenka was her first triumph on Centre Court.

It's back to Court One for the Japanese 14th seed today as, five years on from her fourth, Osaka continues her bid for a fifth Grand Slam title.

Stood in her way is 10th seed Karolina Muchova.

The 29-year-old Czech beat former Wimbledon champion Barbora Krejcikova in three sets in the last round to reach her first quarter-final at the All England Club since 2021.

It is her third in total but Muchova has never made it to the semi-finals before.

The task is quite straightforward, in theory, for Jiri Lehecka. He knows he must win three straight sets, given he's been two down overnight.

And, wow, this is quite the start. Two unreturnable serves, a delicious drop shot and a Zverev forehand balloon error - a hold to love.

And a little warning to the second seed that this might not be over as quick as he'd like.

Image source, Getty Images

Jannik Sinner, speaking on court after defeating Jan-Lennard Struff to advance to the semi-finals: "He is a very, very tough player to play against but he deserves everything he's done and achieved in his career. He's a great person off the court with an amazing team. In the beginning, he started better than me, I was struggling a little bit. I started to serve a little bit better and tried to stay there mentally. I'm happy to be back in the semi finals here.

"The second set could have ended in a different way, tie-breaks are always 50/50. In the third set, I was a little bit more relaxed. His first serve percentage dropped, which helped me play more comfortably. He's a very tough player to play against, very pleased."

On the heat: "We worked a lot after Paris [losing early in the French Open] trying to understand what went wrong and prepared in the best possible way. It was a huge test today, I felt comfortable on the physical side, a good step forwards. If it happens again like Paris, I hope not, we know that we need to change a couple of things again."

Image source, Getty Images

The paying punters on Centre Court have the added bonus of an extra men's singles match this afternoon.

Well, part of one anyway - German second seed Alexander Zverev went two sets up on Czech Jiri Lehecka last night but play had to stop because of the Wimbledon curfew of 23:00 BST.

Zverev - who broke his Grand Slam duck by winning the French Open this year - is bidding to reach the SW19 quarter-finals for the first time and set up a last-eight tie with American Taylor Fritz.

Given he's lost his past seven meetings with Fritz, and that the German will have a day's less rest, Zverev will want to finish things as quickly as possible this afternoon.

World number seven Coco Gauff, speaking on Centre Court after beating Jessica Pegula to reach her first Wimbledon semi-final: "Honestly it is pretty insane, considering I hadn't won a match on grass in two years before this tournament. I'm definitely really happy with how I played today. Jessica [Pegula] is an incredible opponent and person, playing against her is never easy so I'm just happy to get through this one today.

"I knew her balls would be so flat and low, so I just needed to trust that I could hang in the rallies and play the tennis I wanted to play. I started to land more first serves in the court which I think also helped. In the first set, I made a few too many errors rushing out a little bit too quickly in the rallies. But I felt like in the last two sets I played some really great tennis.

"I've been going to three sets almost every match so I feel like when you have that faith in yourself as a competitor, when the match goes the distance or you lose one set, then it stops you from panicking."

On the expectation on her after a successful debut at Wimbledon in 2019: "That might be the case for some people, but I think a lot of people had me going out in the first or second round this tournament - for that reason I'm just happy to get through to the semi-finals. After seven years playing in this tournament, it is the first time I've walked onto Centre Court and not felt nervous. So I don't know if I'm becoming a veteran already?

"It's funny because when they had us waiting before walking onto court, I was looking at all the decorations and the art pieces back there because it is so beautiful. But then I literally had to tell myself to look at the doors so I could focus on the match. I'm just really enjoying the process of being here and playing at Wimbledon this year."

John Lloyd
Former GB Davis Cup captain on BBC Two

Jannik Sinner came through when he needed to there. His serve was brilliant today. He will obviously be happy with three sets going into the semi-finals. You cannot ask for more than that against a dangerous opponent who took his chances and had a lot of weapons going for him.

Sinner just had too much class and played too well on the big points. I would give him a B grade for that performance today.

John McEnroe
Three-time Wimbledon singles champion on BBC Two

Well Jannik Sinner lost to Novak Djokovic in the semi-finals of the Australian Open, so that will give him something to think about. For now, though, he will be happy to be through this match in straight sets. He was set point down in the second set, remember, so this could've been a very different match.

It was a career milestone for Jan-Lennard Struff. God bless him to get there and battle the way he did. I'm glad he got a huge round of applause.

Andrew Castle
BBC Sport tennis commentator on BBC Two

Image source, PA Media

It is five match wins and counting for Jannik Sinner. He can rest and sit back as Felix Auger-Aliassime and Novak Djokovic face off later on.

Facing either one of them in the next round is a thing for another day.

Emily Salley
BBC Sport at Wimbledon

Another job done for Jannik Sinner. It wasn't his best performance and he certainly didn't blow Jan-Lennard Struff away, but he acts decisively in the right moments to get across the finish line.

Greg Rusedski
Former British number one on BBC Radio 5 Live

Jannik Sinner is always the title favourite. He'll be delighted to come out through straight sets but, he hasn't been in any major finals this year.

Huge ovation for Jan-Lennard Struff as he leaves Court One.

The 36-year-old was playing in his first Grand Slam quarter-final but couldn't take his opportunities in the big moments.

He took Sinner to deuce in three first-set service games and had a set point in the second, but couldn't get near the Italian's serve in the second-set tie-break.