Carlos Alcaraz has renewed energy and purpose to his play after that mini dip following the first set.

He backs up a break with an emphatic service game to love, sealing it with his first ace of the match and his 46th of the tournament so far.

New balls.

Watch the moment Jannik Sinner won the fourth set to take the quarter-final against Daniil Medvedev to a decider.

Tommy Paul clinched a brilliant first set with a stunning winner.

Daniil Medvedev mishits a forehand to bring the score to 40-30 before Jannik Sinner forces deuce with a lovely backhand, and couple of volleys at the net.

The Russian holds his nerve to hold, however, with two dominant first serves.

Medvedev clenches his fist and celebrates towards his coaching team.

A real ding-dong contest this one.

Carlos Alcaraz takes the third break point and gives a hearty fist pump. He is back on terms.

Image source, Reuters

Carlos Alcaraz is not done yet.

He bends a backhand into the corner of the court to earn himself three break points. Can he take one?

All the momentum was with Jannik Sinner through that fourth set and, perhaps in an attempt to change that, Daniil Medvedev has taken a short off-court break.

The Russian returns after around four minutes and is on serve.

Greg Rusedski
Former British number one on BBC Radio 5 Live and BBC Sounds

Carlos Alcaraz is being bullied. He's the one usually dictating play, being the boss out there.

It's Tommy Paul who is the boss out there and that's frustrating Alcaraz.

Tommy Paul has his tail well and truly up here as he breaks the defending Wimbledon champion after another bustling game.

Carlos Alcaraz has to dig deep here.

Tommy Paul follows up that first set with a confident hold.

Carlos Alcaraz looks a fraction weary at 15-40 in the second game of the second set.

Is there a window for Paul here?

Michael Emons
BBC Sport at Wimbledon

You are going to struggle to find a better set of tennis anywhere in these championships. It was brilliant and dramatic from start to finish.

Twelfth seed Tommy Paul takes it with an absolute dream passing winner, with Alcaraz at full stretch unable to get there.

Paul jogs back to his seat knowing he's one third of the way to the semi-final, while it is a rueful shake of the head from Carlos Alcaraz.

The reigning champion finds himself a set down.

New balls for Jannik Sinner to serve with and he obliges with an ace.

The world number one sees out the game and wins the fourth set as Daniil Medvedev puts too much fizz into a backhand and it goes long.

Into a fifth set we go...

Andrew Castle
BBC Sport tennis commentator on BBC TV

The defending champion is in trouble here, in the opening set. What a set of tennis, a scrap right from the word go.

Paul is certainly not afraid of the reputation on the other side of net, he’s matching Alcaraz shot for shot.

Wow. A brilliant passing backhand from Tommy Paul and he takes the first set.

A pulsating contest.

Todd Woodbridge
Former Wimbledon doubles champion on BBC TV

I often feel when I have watched Medvedev on grass, when he gets behind he never has the true belief he can get back in it. When he’s level, he’s good.

That’s why we’ve seen him chirping at the box.

We suspect Michael is purring on Court One at the calibre of tennis on show, Pat.

Tommy Paul earns himself a chance to take the set on Carlos Alcaraz's serve.

Daniil Medvedev comes through a service game relatively untroubled but you feel this set may already be beyond him, unless something extraordinary happens.

Jannik Sinner to serve now for the fourth and take this match to a decider.

Naomi Broady
British player on BBC Radio 5 Live and BBC Sounds

It's ridiculous. An hour and four minutes they've been playing. It's just crazy and the level of tennis hasn't dropped off for a single minute.

They've been absolutely at each other's heels. As soon as you feel like one's going to start to pull away, the other one is right behind them.

Tommy Paul has moved with real decisiveness to the net at key moments. After exchanging drop shots he executes a powerful volley to bank the 11th game in his favour.

Carlos Alcaraz, meanwhile, is wittering away to himself during the change of ends. Big game coming up.