Novak Djokovic is looking to force a tie-break as he still hopes to wrap up a win in four sets.

The net cord is against Djokovic again as the ball bounces wide. 15-15.

Pat Cash
Former Wimbledon champion on BBC TV

That's a great hold isn't it.

Some great serving and a scrambled double-handed scoop but it doesn't matter.

Alexei's a great competitor.

Charlotte Coates
BBC Sport at Wimbledon

Novak Djokovic produces a wondrous return to put Alexei Popyrin under pressure from the start of the game.

Pressure can be make or break in sport and it certainly made Popyrin as he saved three break points.

Image source, PA Media

A 120mph serve is returned into the net by Novak Djokovic.

Three defended.

Fine work from Alexei Popyrin who then gains advantage with his 19th ace of the match.

Popyrin rounds off a hectic rally at the net by scooping it back as Djokovic is on his heels.

Wow! A pressure moment and Popyrin comes out shining.

Well, that's one way to respond. Alexei Popyrin comes up with an ace.

One defended.

Novak Djokovic then strikes the net cord and it comes back to his side.

Two defended.

Novak Djokovic on the board first against serve as Alexei Popyrin, at full stretch, lobs it long.

And the Serb goes 30-0 up.

Is this the decisive moment? The crowd believe so and rally behind Popyrin.

Popyrin is long again and Djokovic has three attempts to break.

Image source, PA Media

Novak Djokovic scuffs wide. We've not seen a great deal of unforced errors from the Serb since the first set, but he gets back to 15-15.

Alexei Popyrin challenges as Djokovic looks to have aced down the middle for 30-15. Replays show it was well on the line - you could see the chalk fly in the air when it landed.

Charlotte Coates
BBC Sport at Wimbledon

Fine margins.

Image source, BBC Sport

Image source, Getty Images

Over on Court One, 15th seed Holger Rune has been taken to a fifth set by Frenchman Quentin Halys.

The Dane won the fourth set 7-6 (7-4).

The winner will face either Novak Djokovic or Alexei Popyrin in the next round.

A volley at the net from Alexei Popyrin puts him 30-0 up.

There are no signs of a break here as the Australian drills a 132mph ace down the middle. Fantastic.

Novak Djokovic ends a run of 14 unanswered points from Popyrin on serve with a volley at the net.

But now it's Popyrin who calls on the Centre Court crowd to raise the roof as he serves out the game.

Charlotte Coates
BBC Sport at Wimbledon

Now it’s Novak’s turn! He wants more from the crowd and he certainly gets it.

Something has got to give in this fourth set.

Image source, PA Media

Novak Djokovic continues to dominate on serve with an ace to make it 30-0. He walks across the baseline and stretches out his knee. No signs of major discomfort but he's only a month on from an operation on a torn medial meniscus.

Alexei Popyrin comes back into it and a fine pass of Djokovic at the net levels at 30-30, while drawing a big roar from the crowd.

Normal business resumes as Djokovic serves out for the game and he waves the crowd into action, demanding a big cheer for his efforts.

Charlotte Coates
BBC Sport at Wimbledon

Wow! Incredible noise in hear as Alexei Popyrin passes Novak Djokovic at the net.

The Aussie raises his racquet to ask for more, he’s loving this.

Andrew Cotter
Commentator on BBC Two

Djokovic is up against it a bit in this fourth set – at least, Popyrin is providing more of a challenge.

Charlotte Coates
BBC Sport at Wimbledon

Alexei Popyrin is serving brilliantly in the fourth set. Not even the brilliance of Novak Djokovic’s return game has an answer for it.

Alexei Popyrin scores a 12th consecutive point on serve to take another hold.

Good stuff from the Australian. It's just the small matter of the Novak Djokovic serve that's the problem. But he is keeping up the scoreboard pressure, so that's something.

Novak Djokovic sends a perfect ace down the T to close out another simple hold of serve.

His ace count is up to 14 in this match while Alexei Popyrin has 16.

Image source, Getty Images

To be honest, Alexei Popyrin is not bad at the old serving thing himself. He's just made a few errors. But that is all it takes against Novak Djokovic.

He closes out a hold to love with a big ace to the far corner of the court.

Charlotte Coates
BBC Sport at Wimbledon

Alexei Popyrin is hanging on in there in the fourth set.

There’s been a couple of times where Novak Djokovic has stood hands on hips with a wry smile on his face. He’s not best pleased out here.

Andrew Cotter
Commentator on BBC TV

Since that first set it’s been a masterclass of the Djokovic serve.