Tracy Austin
Two-time Grand Slam champion on BBC One

Jessica Pegula is playing about the same tennis set-to-set, plus or minus a touch, but Coco Gauff has been able to elevate her groundstrokes to a tremendous level from where she was in the opening set.

In the first set, Gauff was at 67mph average on the forehand but she has now gone up to 72mph. She keeps increasing her top spin and she is getting full control of rallies.

Another stunning rally and Jessica Pegula gets to Coco Gauff's drop and whips a passing shot... millimetres wide!

Gauff stands firm on serve despite Pegula showing she doesn't lack for fighting spirit either.

I'm certainly not ruling out another twist - or two - before this one is done.

Emily Salley
BBC Sport at Wimbledon

Hi Harry, thanks for getting in touch! It is pretty hot out on Court One at the minute and Sinner has had problems coping with stifling conditions in the past, but it doesn't really seem to be impacting him too much today.

The top seed just hasn't found his top form at these Championships yet, but he's still good enough to strike decisively in the key moments.

Very stylish! Jannik Sinner goes for a lob but a leaping Jan-Lennard Struff bangs down a backhand smash winner.

A second-serve ace secures the hold.

Jan-Lennard Struff and Jannik Sinner get locked in a baseline exchange, neutralising one another until the German puts a cross-court forehand into the tramlines. Back to deuce we go.

Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live

Who's going to respond best under this immense pressure?

At the moment, it looks like Coco Gauff.

Greg Rusedski
Former British number one on BBC Radio 5 Live

Sinner is getting the job done but he hasn't hit his top level yet.

If he does get through, he cannot play like this. But for now, he has to focus on winning this.

Jannik Sinner misses a forehand. Not to be this time.

Harry Poole
BBC Sport at Wimbledon

We are set up for a big finish to the opening match on Centre Court.

You always want big match-ups to be won by excellence and not errors.

Both players are hinting at improving levels, but the consistency isn't there for either, so I suspect we can probably expect a couple more twists and turns before this one is decided...

Image source, Getty Images

Great Britain's Henry Patten and Finnish partner Harri Heliovaara, the top seeds in the men's doubles, have lost the first set of their quarter-final against eighth seeds Guido Andreozzi of Argentina and Manuel Guinard of France.

You can watch that match or choose an alternative court to view on the BBC iPlayer.

Jannik Sinner hasn't really attacked Jan-Lennard Struff's second serve but on this occasion he doesn't need to, with Struff losing his radar and sending a forehand long. 15-30.

At 30-all, he gets another look at a second serve and this time, he goes for it, hammering deep return after deep return as he creeps up the court before Struff fires one wide.

Coco Gauff has shown throughout this match that she will always fight.

Having finally got her game to a level she'd be happy with, she is broken and the match is back in the balance.

No bother, Gauff comes out firing and breaks Jessica Pegula to love. Big time response - and you should expect no less from a two-time Grand Slam champion.

Tracy Austin
Two-time Grand Slam champion on BBC One

A great job by Jessica Pegula! She just started adding a little sense of urgency and injecting some more energy to her legs. She got down a little lower to her shots and she moved forward more. It was better ball-striking overall with much more aggression behind it.

She is so good at knowing what she needs to do to stay in matches.

Pam Shriver
Five-time Wimbledon doubles champion on BBC Radio 5 Live

Best point of the match by far!

Extraordinary drop shot from Gauff. Pegula read it but the way the ball bounces off this grass, she had no chance.

Another twist in this match!

Just as I was writing that Coco Gauff was looking confident with her serve, there's the double-fault... 30-30.

But what follows is the best point of the match!

A full-throttle rally with both players charging along the baseline before Gauff produces a stunning backhand drop shot.

Another long rally is won by Pegula, though. Deuce and then break point.

First serve in but the return is good and Gauff can only put her backhand into the net. Back on serve in this deciding set.

Image source, Getty Images

Emily Salley
BBC Sport at Wimbledon

Very wholesome.

A little kid shouts out "go Jannik" which earns an "awww" from the crowd and a smile from the man himself.

Image source, Getty Images

Bit loose from Jannik Sinner, blasting a forehand long on the approach. 15-all.

Jan-Lennard Struff wrong-foots Sinner with a brutal forehand winner but then plants a routine stroke into the net. 30-all.

An ace down the T and a forehand drop shot secure the hold for Sinner.

Zverev and Jiri Lehecka will resume their fourth-round match on Centre Court after the conclusion of the Jessica Pegula-Coco Gauff quarter-final.

Zverev won the first two sets and it's level at 3-3 in the third.

We've spotted that for some reason that match doesn't appear in our scores and order of play for today, but we can assure you that that's when it will be!

Emily Salley
BBC Sport at Wimbledon

I'm spotting a lot of orange in the crowd today. Hardly a coincidence given Jannik Sinner is playing.

There's no sign yet of the Carota Boys - Sinner's loyal fan club who dress up in carrot costumes - but I can see a few people dressed head-to-toe in orange, including a father and son duo who are on their feet every time the Italian wins a point.

Oh yes! Down 40-15 and with Jan-Lennard Struff camped at the net, Jannik Sinner slides into a backhand lob which nestles on the baseline. A chasing Struff returns long.

But Struff holds with another 130mph+ rocket of a serve.