And into a tie-break we go on court four...

The serves and big forehands are dominating between Henry Searle and Ethan Quinn, and a untimely double fault from Quinn hands an early mini-break to Searle.

It's advantage to the Brit at the change of ends...

Emma Raducanu holds to love, helped by four first serves in, to back up that break in the opening game.

She has won eight of the first nine points on Court One.

Image source, Getty Images

Pat Cash
Former Wimbledon champion on BBC Radio 5 Live and BBC Sounds

Unless Alcaraz does something and Fognini goes off the boil, I think this could be the biggest upset in Wimbledon history. Fognini is playing unbeleivable tennis and has worked out how to beat Alcaraz.

Everything he does is working, and Carlos is struggling. He is not playing badly, he is just being outplayed.

Jonathan Jurejko
BBC Sport senior tennis reporter at Wimbledon

Carlos Alcaraz's demeanour tells us everything.

At the end of the set, the defending champion leans forward in his chair and asks for another ice towel which he drapes round his neck like a snake.

It's Alcaraz who is hissing. He's completely perplexed at what's happening.

The young Spaniard had enough in that final game of the fourth set, barely trying as he casually knocked the ball well wide on set point.

Fabio Fognini has sauntered off the court for a well-needed break.

Tim Henman
Former British number one on BBC One

It certainly wasn't meant to go like this.

It is always difficult to predict, but I've never seen Carlos Alcaraz look this out of sorts on such a big stage.

He has got to find the solutions in this fifth set.

Image source, Getty Images

Ethan Quinn and Henry Searle are ticking off the games on court four.

American Quinn holds easily to love to keep it all on serve in this third set.

British wildcard Searle now needs to hold to take it to a tie-break.

Harriet Dart maintains her good form in the second set as she seals an early break against her opponent Dalma Galfi.

The British number four forces Galfi to come to the net and her volley goes long.

Another step in the right direction for Dart.

Just the start Emma Raducanu would have wanted.

Maybe some signs of early nerves for Mimi Xu as the Welsh teenager double-faults on the second point of the match, and Raducanu takes the second of three break points to get her first game on the board.

Fabio Fognini forces a deciding set!

You can forget the three-peat for now, Carlos Alcaraz is fighting just to make it through to the second round!

A hold to love.

The first time since 2010 that a defending champion has been taken the distance in the first round at Wimbledon - that was Roger Federer, so it happens to the best of them.

The winner of this match could face 2023 champion Marketa Vondrousova in round two - she's currently taking on 32nd seed McCartney Kessler on Court 12.

Beyond that, world number one Aryna Sabalenka is a potential third-round opponent.

Mimi Xu will serve first in the Wimbledon sunshine.

Andrew Cotter
Commentator on BBC One

Fabio Fognini has a stranglehold on this fourth set. Trouble is brewing for the champion on Centre Court.

The last time a defending champion in the men's singles went to five sets in the first round was Roger Federer against Alejandro Falla in 2010.

The last time the defending champion lost in the first round was Lleyton Hewitt against Ivo Karlovic.

Anne Keothavong
Former British number one on BBC TV

Earlier this year on the tennis court, things have been difficult for Emma Raducanu but she has put herself out there.

She has been competing a lot over the last few weeks and Mark Petchey has been on board as her coach.

They have been working things out and we have seen moments of some really good tennis from her in recent weeks.

Image source, Getty Images

Emma Raducanu's matches at Wimbledon will always garner huge attention, following the Brit's shock US Open victory in 2021.

The closest she has come to repeating that success at a Grand Slam has been at Wimbledon - she has reached the fourth round in two of her previous three appearances at SW19.

She has won 10 of the 12 first-round matches she has played in the main draws of Grand Slams.

Brilliant from Fabio Fognini to bring up another break point.

A fantastic return, he follows it in and confidently puts away the volley.

Carlos Alcaraz saves it with an ace but his next serve is just begging Fognini to hit it, he does so, down the line and brings up another break point.

Alcaraz goes wide and Fognini will serve for the fourth set! Wow, who saw this coming?

Teenager Mimi Xu is making her Grand Slam debut today - the Swansea-born 17-year-old, ranked 318th in the world, was given a wildcard to compete and she has never beaten a player in the top 50 of the world rankings before.

"To get to play my first major Wimbledon, it means absolutely everything to me," she said.

"I've got nothing to lose in a match-up like that, I think I can really go out there and play freely and show everyone what I can do."

Jonathan Jurejko
BBC Sport senior tennis reporter at Wimbledon

As you have gathered, any opportunity to find shade today at Wimbledon is most welcome.

Fabio Fognini decides to step back in the shadows behind the baseline as Carlos Alcaraz goes to his bag at the end of the sixth game.

The Italian sighs like the rest of us in the same situation.

Tim Henman
Former British number one on BBC One

The odds are most definitely on a fifth set right now.

The body language is very flat from Carlos Alcaraz and Fabio Fognini looks like he is having a lot of fun in the sun.

Next up on Court One, it's an all-British first-round tie as teenage wildcard Mimi Xu takes on former US Open champion Emma Raducanu... and the two players are heading on to court now.

There are a few empty seats at the moment following the end of Jacob Fearnley's match, but I'm sure they'll fill up soon enough.

It's the first time that two British women will face each other in the first round of Wimbledon since 2011, when Anne Keothavong faced Naomi Broady.

Superb overhead volley from Fabio Fognini to move to within a point of consolidating the break.

He advances and whips a forehand into the corner to do just that.

Carlos Alcaraz was talking frustratedly to his box during that game. What has the defending champion got left as he tries to avoid a fifth set?

It's looking good for Britain's Billy Harris against world number 118 Dusan Lajovic as he gets the early break of serve in the third set.

Portugal's Nuno Borges awaits the winner of this tie in the second round.