Jonathan Jurejko
BBC Sport in Melbourne

Why do we continue to be surprised by Novak Djokovic?

The guy is more durable than Stretch Armstrong and has the heart of Maximus Decimus Meridius.

How can you not be entertained.

Djokovic has ramped up the aggression since tweaking his groin, upping his serve speed and going for broke with his groundstrokes.

A necessary tactic and one which is serving him well. Let's see if that's enough to outlast Alcaraz...

Image source, Reuters

A second serve ace at 117mph. Not bad at all, Novak.

Carlos Alcaraz nets, and then fires long. The third seed is furiously mumbling to himself in between points.

He's struggling to find a way past Djokovic, who grabs the hold fairly comfortably.

That's better from Carlos Alcaraz, forcing Novak Djokovic into the miss before wrongfooting the 24-time Grand Slam champion with a fiery forehand winner.

Djokovic really should bring us back to deuce as the ball pops up nicely, but he launches it straight into the net.

Carlos Alcaraz fends off the break point, but the longer rally goes Novak Djokovic's way again and he's got another chance.

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

I think Djokovic knows he can go into that backhand side and not get burnt quite as hard as he does with the forehand side.

It's quite evident there is a little bit of difference between the two.

When coaches talk about Jannik Sinner, they always say how equal those sides are but I think with Alcaraz it definitely feels like the forehand does more damage.

Image source, Getty Images

Shottt. It's a brilliant serve from Carlos Alcaraz but the Spaniard doesn't do enough on Novak Djokovic's return and the Serb swerves squeezes it past Alcaraz and in to bring up a break point.

Novak Djokovic wriggles free with a forehand winner before Carlos Alcaraz pushes the next point into the net.

Over to you, Carlos.

Novak Djokovic looked like he would have trouble even making it into a second set, never mind going on and winning it in the way he has just done.

He picks up where he left off, with big serving helping him to a 40-15 lead but Carlos Alcaraz reacts quickly to the drop shot and plays a pass down the line before clawing his way to deuce.

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

I can't believe what we have just witnessed!

I thought this was going to be a straight sets match, Alcaraz in charge, an injured Djokovic. I thought he would have no chance of levelling this match, so how on earth he has done that?

He has dug deep, remained very calm, served well and started to become aggressive. He has started coming forward a bit more and it has paid off.

Novak Djokovic takes the set points at the first opportunity with a magnificent backhand winner down the line.

We have some match here.

Image source, Reuters

Novak Djokovic - a 10-time winner in Melbourne - has some strong support here today and they're loving what they see as the Serb rockets a forehand winner for a 0-30 lead.

He then brings up three set points with a magnificent return.

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

That was very nonchalantly hit!

I don't think Novak Djokovic has the energy in his legs to go up for the smash and then he didn't have time to get out of the way of it, so it was a beautiful backhand volley.

Very classic - almost grass court style.

Carlos Alcaraz whips a fine forehand winner down the line to nudge ahead in this game.

We now have a short pause as something, which appears to be bird poo, is cleaned up off the court.

Djokovic fights back, bringing out a remarkable backhand volley before securing the hold as Alcaraz goes agonisingly wide with a backhand down the line.

Novak Djokovic stutters as he tries to return a powerful Carlos Alcaraz forehand - he's still not quite 100% physically.

Spanish third seed Alcaraz goes on to hold to love.

Image source, Getty Images

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

The talent Djokovic is up against tonight is just mesmerising.

Alcaraz is very charismatic, he brings enormous personality onto the court, he has this joyful spirit and he is smiling all the time. He just loves what he can do - I think he loves entertaining himself to be honest as well as the crowd out here.

They are really being treated to something special.

Novak Djokovic speeds into a 40-0 lead with some strong first serves before Carlos Alcaraz fights back.

At 40-30 Djokovic secures the hold with an overhead smash at the net.

The Serb takes a deep breath as he walks over to his seat at the change of ends.

A second break point of the game for Novak Djokovic but a huge serve from Carlos Alcaraz makes the save.

This has turned into a key game in this second set.

Djokovic then has his hands on his hips after missing a forehand and Alcaraz gets the hold with another dropshot.

Alcaraz sticks his tongue out and shakes his racquet in celebration.

Some "let's go Novak, let's go" chants greet a break point for Djokovic, but the Serb can't make it count as Carlos Alcaraz's drop shot wins him the point.

The pair then trade points before Djokovic comes out on top of a rally to force a fourth deuce of the game.

Image source, Getty Images

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

Djokovic is walking strangely. Even in between the points something doesn't look quite right.

Alcaraz is being so smart. He is just pushing the ball into that forehand corner, which is where it hurts.

Novak Djokovic's movement appears stifled again as he is slow getting to a Carlos Alcaraz forehand from the baseline.

Djokovic goes just wide with a forehand pass down the line, but fights back well to force deuce with a couple of powerful forehands.