Zverev into the net, and he drops his serve for the third successive time.

Djokovic has won the past six games. Unless something remarkable happens, it feels like we are rapidly approaching the denouement in Paris.

And at the worst possible time, Zverev chucks in his first double fault of the match...

Zverev serves first in this fourth and potentially final set.

The third point sees another epic rally, again won with a dabbed backhand volley by Djokovic. That shot has been the story of this match.

15-30, Zverev badly needs to hold here.

Novak Djokovic won all but one of the 14 points from his first serve in that third set.

Zverev meanwhile piled in 10 unforced errors to three from his opponent.

If Zverev finds a second wind, we could be in for a long night. But on current evidence, we may be done before the pubs close.

Djokovic holds to love and is a set away from the semi-finals.

Jonathan Jurejko
BBC Sport senior tennis reporter at Roland Garros

Djokovic's greater clarity of mind is tipping this contest in his favour.

He's dictating the patterns of play and, crucially, knowing the right time to pull out the drop-shot.

Djokovic has attempted 23 so far and they're working out a treat.

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

Image source, Getty Images

Zverev's brain is fried at the moment. Mentally he's disappearing and losing confidence.

The point to secure the double break came after an exchange of volleys. Zverev looked to have found a legal winner, but it was called long and confirmed by the umpire checking on court.

Zverev did not even have the energy to contest that one. He looks in a very bad place.

Alexander Zverev has been complaining to his coaches more and more as this match has gone on. You fear the pressure may once again be getting to him.

Another backhand flies long, and Djokovic has another two break points.

And the first is converted!

Daniela Hantuchova
Former world number five on BBC Radio 5 Live and BBC Sounds

We were saying this match needed another gear and Novak is definitely the one forcing it now.

Hear BBC Radio 5 Live commentary via the "Listen live" link at the top of this page.

We spoke earlier about the importance of points won from the first serve in this match.

In set three, Djokovic has claimed 90% of those. And that is proving decisive.

Djokovic holds to 15, consolidating his break.

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

Image source, Getty Images

I feel like Novak's level has really jumped since the middle of the second set. He feels more comfortable with his movement and his shot selection.

That "game-on" face is turned to the sky as Djokovic spurns the first break point.

However he recollects and drags Zverev virtually from La Rochelle to Strasbourg on his way to setting up a second break chance.

Then Zverev skews another forehand wide! A potentially priceless break.

Daniela Hantuchova
Former world number five on BBC Radio 5 Live and BBC Sounds

Novak is starting to have that "game-on" face and he is starting to sense an opportunity here.

That's the best point Zverev has won all match - twice digging out what seemed a certain Djokovic winner on the verge of the second bounce before, while running backwards, sending a brilliant winner down the line that left his opponent standing.

But he follows it up with a couple of junk points and Djokovic is 15-30 ahead. Zverev's inconsistency encapsulated.

The German does enough to pull back level in the game, but then loses out in an epic backhand rally.

Break point to the veteran...

We'd love to hear your thoughts on everything Roland Garros-related today.

Who are you backing to win the men's singles? There are five strong options remaining - Sinner, Musetti, Alcaraz, and the winner of this match.

Let us know who, and why, using the details above.

Image source, Getty Images

After 16 successive points on serve, Djokovic sends one long and it's 30-15.

But Djokovic is in no way rattled, flicking in another perfect backhand slice to frustrate his foe.

On we go on serve.