Annabel Croft
Former British number one on BBC Radio 5 Live

It is just that unleashing of power from Fonseca, he just thunders it through the court. I have never seen anything like it, the way he is exploding onto the court.

Annabel Croft
Former British number one on BBC Radio 5 Live

Fonseca couldn't have played that game any better. He has taken his tennis to Djokovic and he is playing the match of his life.

This match has now lasted longer than Novak Djokovic's second-round epic - it's three hours and 45 minutes so far and it looks like we may yet have another set.

Image source, Reuters

Joao Fonseca beats his heart with his fist after some brilliant defence followed by a wrong-footing forehand.

And the Brazilian resists some fabulous Djokovic play to earn a break point.

And he breaks with a superbly worked point, again wrong-footing Djokovic with a forehand approach shot.

He will serve for the fourth set.

Image source, Reuters

This set has now lasted an hour.

Joao Fonseca goes 30-0 up but then lets Novak Djokovic back in with an unconvincing second serve.

Fonseca then roars as he unleashes a huge backhand winner.

Djokovic is furious with himself when he nets a backhand and then shanks another one to allow Fonseca to hold.

Image source, EPA

Finally, Djokovic is able to finish off his service game.

Joao Fonseca looks really frustrated at not having seized his opportunities in that game.

But he needs to put that aside because now he is serving to stay in the match.

Well, of course Novak Djokovic saves the break point with a huge ace.

Joao Fonseca nets with a backhand on break point and bangs the ground with his racquet in frustration.

But he gets another chance after a tired-looking shot from Novak Djokovic.

A couple of tired shots from Novak Djokovic - he over-reaches for a backhand which flies long. 15-30.

Every point now is being greeted by a massive roar from the crowd.

Joao Fonseca unleashes another big forehand - he's got a break point!

Image source, Getty Images

Joao Fonseca saves the break point with a huge second serve that Djokovic somehow manages to get back, but Fonseca then blasts a forehand winner.

The young Brazilian then wrong-foots Djokovic to secure the game, and tries to get the crowd involved.

Not that they need much encouragement - they are loving this.

Here we go, a couple of well-worked points from Novak Djokovic and he's got two break points.

He nets the first but Joao Fonseca still has another to face...

Annabel Croft
Former British number one on BBC Radio 5 Live

Djokovic looked absolutely drained throughout that entire point and he still managed to manipulate Fonseca.

That'll be just what Djokovic needs, a relatively straightforward service hold.

He even wins a bizarre point in which he almost forgets to move for the ball and ends up awkwardly reaching for it and stabbing it over the net.

Joao Fonseca makes no mistake about holding this time, beginning the game with a beautiful drop shot that even Novak Djokovic has to applaud.

Djokovic is bending over a lot between the points. What has he got left in the tank?

Annabel Croft
Former British number one on BBC Radio 5 Live

Djokovic is fighting hard. He is suffering big time.

Novak Djokovic is wiping his brow and stands hunched over his towel box in between points but is enjoying a much more dominant position on the baseline during the rallies.

Encouraging signs as he holds to 15. He leads 3-2 in the fourth set.

Image source, Getty Images

And there it is! Novak Djokovic steps inside the baseline to receive a second serve and his powerful return is too much for Joao Fonseca.

We're back on serve on Philippe-Chatrier.

Joao Fonseca is coming up with all of the shots! He chases down a drop shot, forces Novak Djokovic into a smash, and then plays a delicate drop winner of his own which spins away from the Serbian - simply lovely. 30-0.

However, if there's one man who doesn't know when he's beaten, it's Djokovic and with the help of a couple of errors from the teenager, he's got a break point.

Annabel Croft
Former British number one on BBC Radio 5 Live

Djokovic is trying to ignite the fire with his anger.

Image source, Getty Images

Novak Djokovic has been shaking his arm and rotating his shoulder quite a bit early in this fourth set.

Joao Fonseca wallops a backhand winner from halfway up the court for 40-30 but Djokovic completes the hold, not that you could tell from his expression.