Jonathan Jurejko
BBC Sport in Melbourne

About to hit the hour mark and we're only nine games in. Nine!

No wonder the restless ones in the Laver crowd have felt the need to move.

Empty the bladder, refill the belly... and still maybe back in time for the next changeover.

Alexander Zverev has had his opportunities. Five of them, in fact.

But the German second seed has not been able to rise to the big points so far, and now he faces a really important game at the business end of this first set.

Impressive serving helps him make a positive start at 30-0.

With minimal backlift, Novak Djokovic knocks a clean backhand winner down the line for game point but then drops a forehand short to keep Alexander Zverev interested.

The former world number one again shows his quality with a forehand winner - and this time gets over the line with an energy-saving ace.

It has been a rather strange first set, but now Djokovic has it within his sights.

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Novak Djokovic knocks the ball up in the air in muted celebration after saving yet another break point.

Alexander Zverev swings his racquet in frustration after once again letting Djokovic off the hook.

The German is being far too passive in these big moments.

Jonathan Jurejko
BBC Sport in Melbourne

Djokovic wearily goes over to grab his towel before another break opportunity for Zverev.

The Serbs in the crowd - and there are plenty of them as always here - rally their man.

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Novak Djokovic turns in frustration after netting a forehand and exchanges words with his team, with Alexander Zverev now getting a look at 15-30 on his opponent's serve.

Oh! That's really wide from Djokovic and Zverev will have a break point!

A double fault from Alexander Zverev gives Novak Djokovic - fully aware a breakthrough here will leave him serving for the set - a 15-30 advantage.

But Zverev escapes impressively with back-to-back aces to avoid any trouble here.

Both players stare into space as they sit in shade during the change of ends.

You suspect it will be Alexander Zverev with more thoughts racing through his mind after missing those four massive break point chances to assert himself in this opening set.

It feels like this is there to be won by whoever can find a period of consistency at the business end of set one.

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Alexander Zverev stares at his team after failing to get to grips with Novak Djokovic's serve early on in this latest game, but the German recovers to deuce with a couple of morale-boosting winners.

But, having again created an opportunity for himself, Zverev can't make anything of it as Djokovic serves his way to safety.

After a positive hold of serve for Novak Djokovic, Alexander Zverev responds with a somewhat surprisingly straightforward hold of his own, sealed with back-to-back aces.

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Jonathan Jurejko
BBC Sport in Melbourne

What a difference landing first serves makes.

Novak Djokovic breezes through a service game, finally, after nailing all five of his first attempts.

The crowd don't really know what to make of this so far, with both players struggling for rhythm.

Alexander Zverev appears to be going through the motions, while there are signs Novak Djokovic is being limited - certainly on serve - by the thigh issue which has disrupted his training in the lead-up to this match.

That's a comfortable hold for the Serb, however.

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Jonathan Jurejko
BBC Sport in Melbourne

Here's Mr Angry!

We've been talking about how calm Djokovic has been most of the tournament.

Now he's letting rip at his box.

Not sure exactly what has riled him, but immediately turns to his team when Zverev holds and unloads in their direction.

Great recovery from Alexander Zverev - but he had to hold his nerve there as Novak Djokovic tested his focus by forcing the German to play three consecutive overheads.

And from 0-40 down, Zverev reels off five straight points to keep us on serve.

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From missing four break points, Alexander Zverev must now face three on his own serve following a series of poor unforced errors.

The German is going through a real tough patch after appearing to make a promising start.

Jonathan Jurejko
BBC Sport in Melbourne

Djokovic will be thanking his lucky stars that he's not dropped serve.

Zverev completely let him off the hook with those awful mistakes.

The frame into Row D on game point pretty much summed it up for the German.

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We've had three games in 25 minutes following that 10-minute slog on Novak Djokovic's serve.

Depending on how Djokovic's leg holds up, we could definitely be in this for the long-run, folks.

The record 10-time champion has popped a cap on. Maybe that was the issue all along.

Novak Djokovic is really, really struggling on his first serve. Is this the thigh issue?

The Serb has managed to put just four of 20 first serves in play so far. Wow.

But Alexander Zverev fails to take any of his four glaring opportunities and we remain on serve.

I'm not sure who that game was more frustrating for, to be honest. A real strange one.

Image source, Getty Images

Jonathan Jurejko
BBC Sport in Melbourne

The amount of ball bouncing that Djokovic does before a serve always tells a story.

He's going into double figures before each one at the moment.

Taking as much time as possible to preserve energy and, perhaps, frustrate Zverev.

Novak Djokovic manages to close down a drop shot but can't get the ball back in play as Alexander Zverev brings up break point number four, but once again Zverev allows a huge opportunity to slip by as he frames a forehand into the Melbourne sky.

Both players are getting a bit fed up with this game now.