Jonathan Jurejko
BBC Sport senior tennis reporter at Roland Garros

We know how reliable Zverev's backhand is. And we know how he can throw in a wobbler of a forehand.

Pushing that one wide down the line, gifting Djokovic two break points, is met with some gasps of horror.

Zverev's response at losing serve is putting hands on hips and staring at the floor.

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

We are seeing the first lapse of concentration from Alexander Zverev here.

The German has made a few easy unforced errors and it looks like he is just trying to force it a little bit.

I think he will be very disappointed with that because he made three unforced errors to lose his serve - one easy forehand and two routine backhands. He never misses those.

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Zverev has slightly dropped a level after his very professional opening set. He's hit six unforced errors already in set two - the latest helps Djokovic on his way to two break points.

The German sees off one with a booming serve out wide, but then sends a backhand long!

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The Phillippe-Chatrier crowd - known for being boisterous in evening matches - are starting to make themselves heard. We are hearing more and more voices crying out between points and as players prepare to serve.

Knowing how combustible both of these men on court can be, that's one to keep an eye on.

The average point length in this match so far has been six shots, with a longest rally of 29.

There have been some worldies among those shots too. This match is shaping up to be as good as we hoped.

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Another world class rally in this game, ending in another well-judged drop shot by Djokovic. The crowd correctly roar their approval.

Zverev responds in the following point. Having kept in it with a couple of looped shots, he ends matters with a blistering backhand down the line. It even draws brief applause from his opponent.

But then Zverev gets a forehand all wrong, sending it long. You can hear him berating himself.

Djokovic serves it out.

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

I certainly feel Novak Djokovic needs to be more aggressive in this second set. He has to start being the boss right now because it feels like Alexander Zverev is controlling the play at the moment, making all the choices and decisions.

Djokovic wants to use the drop shot to pull Zverev forward, but we haven't seen him taking the ball on or willing to come forward at times.

It is all too comfortable for the German at the moment.

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While that first set was the only one dropped by Novak Djokovic so far at Roland Garros, he has had to spend significantly more time on court so far than Alexander Zverev.

Zverev has won his four matches in eight hours and 12 minutes - helped by Tallon Griekspoor's retirement in round four - while Djokovic has needed nine hours and 25 minutes to progress.

In what could be such a tight and possibly exhausting match, might this prove a factor?

A slight delay at the start of this game as the spidercam was too low and getting in Alexander Zverev's eyeline.

The German shrugs off that distraction and holds to 15.

Jonathan Jurejko
BBC Sport senior tennis reporter at Roland Garros

Not a great deal in that first set, truth be told.

Djokovic's lack of precision in the opening game is what cost him.

While the veteran Serb found his rhythm and traded well from the baseline, Zverev getting that dangerous first serve going was enough to keep his opponent at bay.

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That first set was the first lost by Djokovic at this French Open.

He does however win the opening game of set two.

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

Alexander Zverev is doing an incredible job of being super fast to the ball.

He is running towards the drop shots well. He definitely knew Novak Djokovic would be throwing in a lot of them tonight.

Djokovic hasn't hit a bad drop shot yet and Zverev has looked comfortable getting there every time.

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The very first point of the game leads to debate. Alexander Zverev is again convinced the ball is out.

Louise Engzell descends from her chair and disabuses him of that notion.

That final point of set one was Zverev's first ace of the match. All about timing.

Djokovic hit more winners than Zverev in the opening set, but made 10 unforced errors compared to seven from the German.

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

In order to break Alexander Zverev's serve here, Novak Djokovic needs to make him go up the line.

He needs to really cover the cross-court shots from Zverev and make him come up with some shots that are a little bit more uncomfortable.

The good news for Djokovic is that he has sailed through most of his service games so far.

Zverev's average first serve tonight is 134 mph. How do you deal with that?

Djokovic cannot capitalise on a slower second serve, almost slipping as he chases a drop shot before being unable to catch the return.

40-0, three set points for the third seed... he just needs one, ace!

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Jonathan Jurejko
BBC Sport senior tennis reporter at Roland Garros

A few giggles as Zverev decides not to even bother chasing the ball while stranded near the doubles line at 40-0 down.

Fair play. Saving his energy for the huge service game coming up...

The drop shots are back, Ted.

Djokovic plops a perfectly measured one over the net at 15-0. His seventh point won via that method so far.

His serve is also proving potent, as he hits his third ace of the match on his way to holding to love.

But now, Zverev serves for the set...

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Zverev follows up that epic save with two clinical serves.

Djokovic is now serving to stay in the first set.

The rally which Zverev won to save the break point was 29 shots, the longest of this match so far.

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