Tracy Austin
Two-time Grand Slam champion on BBC One

It was not surprising to see Coco Gauff taking a toilet break after 39 minutes, just giving herself time to think about what happened in the opening set.

For her first time on Centre Court, Karolina Muchova didn't seem to be overwhelmed by the moment, the occasion and the history of the court - it is the most magical court in our game.

Coco Gauff opens serve in the second set. She lost the first set in both her previous matches, and needs to complete the hat-trick to keep her Wimbledon dream alive today.

And back to back aces to secure the first game indicate that we may see more fight from the American here.

Emily Salley
BBC Sport at Wimbledon

Coco Gauff threw her towel over her shoulder and stormed off court. A bathroom pep-talk very much needed.

Just 39 minutes for that first set, where 12 unforced errors from Coco Gauff prove costly.

Gauff has left court during the break, looking deeply unimpressed with herself. Karolina Muchova has stayed outside, an ice pack clutched to the crown of her head.

Image source, PA Media

Coco Gauff may lack consistency, but she can hit some splendid shots. A powerful hit puts her 15-30 ahead as Karolina Muchova attempts to serve for the first set.

But Muchova draws oohs from the crowd as a winner down the line is shown by the video replay to have just clipped the chalk, then Gauff goes long to give the Czech a set point.

And sealed with an ace! Superb from Muchova so far.

Image source, EPA

Tracy Austin
Two-time Grand Slam champion on BBC Two

The forehand from Karolina Muchova has always been a dangerous shot but it has improved because it is more reliable.

Coco Gauff belatedly finds her serving range, sending down a couple of 120mph-plus efforts. She then executes a lovely backhand slice and pumps her fist.

But Muchova is again a brick wall, winning all the rallies and showing far more control over her strokes. She forces another deuce on the Gauff serve.

Then it's shot of the day so far from Gauff! A brilliant stunned volley that bounces twice near the net before Muchova can rush in to meet it - however she follows it with another wayward effort. Back to deuce, and story of the day so far for Gauff.

Eventually Gauff sees it through, breaking Muchova's run of five straight games.

Marcelo Arevalo and Mate Pavic have won the first set of their men's doubles semi-final against Kevin Krawietz and Tim Puetz on Court One.

Serve has been dominant so far, with no breaks in the opening 12 games.

Krawietz and Puetz won six straight points after going 4-0 down in the tie-break, but then missed three set points before Arevalo and Pavic won it 10-8.

Great Britain's Henry Patten features in the second semi-final alongside Finnish partner Harri Heliovaara, which immediately follows this match.

This match and all other courts at Wimbledon are available to watch uninterrupted on the BBC iPlayer.

Bailie in Andover: There's not been Muchova fight so far! I'll close the back door on my way out.

We see what you did there...

An initially great response by Coco Gauff to falling a double break behind, suddenly she is 0-40 up on Muchova's serve.

But Muchova remains calm, saving the first two break points then pulling Gauff back and forth across the court before a backhand volley secures deuce.

Gauff is the picture of frustration as she concedes advantage with a shot into the net, the goes long as a huge change goes begging.

Image source, Getty Images

Emily Salley
BBC Sport at Wimbledon

Oh dear, that faulty forehand is causing Coco Gauff a whole pile of problems early on here.

Each one is followed by a groan on Centre Court, with the majority of the crowd very clearly backing the 22-year-old American.

Laura Robson
Former British number one on BBC Two

This morning the club offered the two semi-finalists, who haven't played a match on Centre Court, the opportunity to have a half an hour's practice at 11.00 BST.

I met them to take them through the clubhouse at 10:55 and what really stuck out to me was how much Karolina wanted to soak up everything about the walk through and she was asking what happens in each room.

They were taking pictures by the trophies and she wanted as much information as possible, just to mentally prepare for the occasion.

When she came out with the team, they took a group photo.

Muchova was absolutely loving every possible moment. What stood out to me was how much she had mentally invested into this match.

She wanted to know every inch of detail to make sure she was as ready as possible.

Image source, EPA

There is Hollywood glam in the Royal Box today, with actors Cynthia Erivo and Priyanka Chopra among those in the audience - as is BBC presenter Gabby Logan, taking a break from her World Cup coverage.

They are watching a shaky performance from Coco Gauff so far, who seems to be trying to hit the ball too hard and is making a fair few unforced errors.

Gauff then attempts a drop shot which is thoroughly punished by Muchova for 15-40, before the American gets a smash all wrong to hand the double break to the 10th seed.

Emily Salley
BBC Sport at Wimbledon

There is a bit of a breeze on Centre Court, which is lovely for the crowd and us in the media seats with the temperature set to reach 33 degrees Celsius today, but it could cause some havoc for the players.

Image source, Getty Images

Karolina Muchova may not be a household name, but by reaching the last four at Wimbledon she has now reached the semi-finals of all four Grand Slams. She is a experienced player to be reckoned with.

She doesn't panic after falling 0-30 behind on her serve, or when a sloppy forehand into the net hands two immediate break-back points to Gauff. Muchova reels them back in and takes us to deuce.

A wide forehand from Gauff means Muchova consolidates her early break.

Emily Salley
BBC Sport at Wimbledon

There's a groan as Coco Gauff lands her first double fault of the match. How many of those will we see today?

The American leads the WTA Tour for the most double faults this year with a whopping 226 - 47 more than anyone else.

It's not always a pleasant experience watching Gauff's service games.

Marion Bartoli
Former Wimbledon champion on BBC Two

95% is the occasion and 5% is the tennis.

We all know they can both play but it is about who can navigate the pressure and make the other one feel uncomfortable.

Coco Gauff has won two Grand Slams at such a young age and she knows how to deal with those matches and win seven matches in a row - that is a huge advantage.

Tracy Austin
Two-time Grand Slam champion on BBC Two

Coco Gauff has had 29 double faults, the most of anyone left in the semi-finals.