Annabel Croft
Former British number one on BBC Radio 5 Live and BBC Sounds

At the start of the match, these two were having some longer drawn-out rallies and we thought that it would be an epic battle, but it hasn't really been like that. It has been clunky, awkward and tense.

I also feel like you can't take your eyes off what Alexander Zverev is doing because Jannik Sinner has just been maintaining what he usually does.

This is around the time when it went wrong for Alexander Zverev in the first set, so a hold of serve here is crucial for the German.

Ferocious ball-striking from Jannik Sinner and while Alexander Zverev does well to absorb the power, he's left with no chance as the defending champion fizzes that forehand winner past him.

And there's another huge winner for Sinner, who missed out on love hold by firing long.

He gets it at the next time of asking though as Zverev repays the favour with an overhit forehand.

Image source, Getty Images

Annabel Croft
Former British number one on BBC Radio 5 Live and BBC Sounds

I think these sprints might start making Alexander Zverev feel a bit better.

But he just needs a couple of points back-to-back to just get things going, get the crowd going and start feeling better about himself.

This time the drop shot fails for Jannik Sinner as Alexander Zverev scurries to the ball and is able to fling the ball back down the line.

The world number one can't do much about Zverev's next serve and despite crouching down to get there, he skews the return into the skies and the ball drops beyond the baseline.

That would have been a classy cross-court winner from Jannik Sinner after being sent out so wide by Alexander Zverev, but it misses the line by just an inch or two.

The German fires down a booming ace, but there's absolutely no stopping that brutal backhand from Jannik Sinner. 30-30.

Annabel Croft
Former British number one on BBC Radio 5 Live and BBC Sounds

I think Sinner can just go into that Zverev forehand knowing that he is safe there.

That forehand isn't doing anything at the moment - it is just sitting up, it is mid-court, it is bouncing up quite high, it isn't penetrating through the court - so it's not going to harm him.

I get the feeling that Sinner feels he is on top of these rallies.

Image source, Getty Images

After that first drop shot worked so well, Jannik Sinner goes for it again and despite Alexander Zverev getting there in time, he isn't able to lift it over the the net.

The second seed looks furious with himself as he finds the net again and gifts the hold to Sinner.

Jannik Sinner hasn't utilised the drop shot much today, but it pays off brilliantly there with Alexander Zverev having no chance of reaching it.

But now it's the defending champion's time to double fault and then net - pulling his opponent level at 30-30.

Annabel Croft
Former British number one on BBC Radio 5 Live and BBC Sounds

I guess you can understand Alexander Zverev looking down right now.

He invested 45 minutes to get through that first set and he kind of dropped away throughout it. His level wasn't getting better, it was actually being dismantled in a way.

He has left that first set with less confidence than when he started.

I think he's probably trying to work out what on earth do I do with this guy...

Image source, Getty Images

Jonathan Jurejko
BBC Sport in Melbourne

The tennis court is a lonely place to be when your confidence is teetering.

Ask Alexander Zverev.

Not much clarity of thought for the German at the moment. That was illustrated when he let a high ball from Sinner go over his head and he needed to run back around it.

The groans from the crowd when he coughs up another double fault can't have been helpful either.

Good judgement from Alexander Zverev to leave that one and see the ball fizz long. That wraps up the hold.

Alexander Zverev does brilliantly well to stay in that point, twisting with his back to court before twirling into the backhand. He stays in the rally and it's Jannik Sinner who misses first.

A double fault follows. 15-15.

An angry swipe of the racquet from Alexander Zverev after he pushes the ball into the net. He's not happy.

Jannik Sinner punishes a lacklustre slice from the second seed before sending down a brutal forehand that Zverev can only loop long.

And there's the hold. Easy work for Sinner.

Image source, get

Jannik Sinner very nearly brings us back to deuce after reaching the drop shot, but his shot clips the net and it trickles back onto his side of the court.

A big sigh of relief for Alexander Zverev as he digs deep to hold.

That's a great smash from Alexander Zverev as the ball just pinches the baseline to claw the first break point back.

And there's another superb smash from the German to take us to deuce.

Image source, Getty Images

Ooh. Jannik Sinner looked like he had that point in the bag, but the net catches him out as he goes for a forehand winner down the line.

But oh dear. Alexander Zverev is talking angrily towards his team as a double fault hands the defending champion two break points.

Alexander Zverev is in a bit of bother now. Two big misses on his own serve and there is an opening for Jannik Sinner. 0-30.

The misses keep flying off Alexander Zverev's racquet and it makes life easy for Jannik Sinner, who claims a straightforward hold.

Annabel Croft
Former British number one on BBC Radio 5 Live and BBC Sounds

Alexander Zverev's dad is once again down courtside and he is saying plenty to him.

Whatever he is saying is very direct and really strict.

I would feel like I need to do what he is saying.

Image source, Getty Images