Pat Cash
Former Wimbledon champion on BBC Radio 5 Sports Extra

Novak Djokovic is in control now, isn't he?

He's got to keep coming into the net. He's realised that Dino Prizmic is not missing much. He has to create errors and get Prizmic off balance but it's been a long time to get to this stage.

Delightful tennis from Novak Djokovic, who is getting better as Dino Prizmic's challenge begins to fade. He makes a delicate backhand drop shot at the net for 0-30 and a miss from the 18-year-old sets Djokovic up for two break points.

Novak Djokovic seals a comfortable hold to back up the break and take charge of the fourth set. Is this the start of a sprint to the finish line?

It'll be interesting to hear Novak Djokovic's thoughts on this one, assuming he does come out on top as is beginning to feel increasingly inevitable.

A forehand winner brings the world number one to 40-0 and Dino Prizmic may be just starting to pay for his efforts over the course of the first three hours of this entertaining contest.

Image source, Getty Images

The 10-time Australian Open champion is being made to work hard on the opening day in Melbourne...

Wide from Prizmic, and with that Djokovic claims the early break in the fourth set.

Has he broken the teenager's resistance once and for all now?

Pat Cash
Former Wimbledon champion on BBC Radio 5 Sports Extra

I'd say this is one of the most unexpected challenges Novak Djokovic has ever had defending a title.

Dino Prizmic has played incredibly well. Just after halfway through the third set though, some unforced errors were creeping in.

Djokovic is having to play at his absolute best in the first. That's not what you want as a 36-year-old!

Dino Prizmic makes no mistakes with an overhead to edge ahead on serve but he nets a backhand to bring Novak Djokovic to 30-30.

He needs a positive start to the fourth set and he gives himself the chance to achieve just that with a forehand winner which draws applause from the top seed, but he can't take his opportunity.

Three hours on the clock after a third set lasting one hour and 11 minutes.

I'm not sure many predicted Dino Prizmic would be capable of making Novak Djokovic work this hard for a first round victory at the Australian Open.

But it is the world number one who leads by two-sets-to-one on Rod Laver Arena.

Can the teenager take us to a fifth?

Image source, Reuters

There was nothing Dino Prizmic could do there. The Croat hangs in the rally as long as he can before Novak Djokovic works the space and forces his opponent into the net.

And the world number one lets out a huge roar as he wraps up a third set he was made to work so hard to take, with a fourth game in a row - after being broken for a second time - leaving him a set from victory.

Jonathan Jurejko
BBC Sport in Melbourne

The crowd on Rod Laver Arena seems to be split three ways by nationality: Aussie, Serb and Croat.

Reckon quite a few of the locals joined in earlier when 'Di-no, Di-no, Di-no' rang around the stadium.

As much as they love Djokovic here, plenty like to see a shock.

Don't think Djokovic was impressed by that show of support for his opponent, though. He never is.

He feeds off that energy and, when he goes 5-3 ahead, the Serb cups his ear to the crowd.

Lots of Serb fans jump to their feet and you can see dozens of national flags being wafted in the slight Melbourne breeze.

Back comes Novak Djokovic, of course.

The defending champion is two points from the set at 30-30 - but he knows he won't be getting much for free here.

Who forgot to hand Dino Prizmic the script before he walked out on to Rod Laver Arena?!

It's fearless tennis from the teenager, who is refusing to fade away and moves 0-30 up.

Jonathan Jurejko
BBC Sport in Melbourne

Will the real Novak Djokovic please stand up?

He's not gonna have a problem here. He is having a problem here.

Dino Prizmic looks the real deal and having to face this level of quality so early on in a Grand Slam seems to have befuddled Djokovic.

But - as we have seen sooooo many times - when the going gets tough, Djokovic gets going.

How long can Prizmic hang with the GOAT?

Dino Prizmic made the world's top 200 for the first time five months ago, but here he is slogging it out with the world number one at his favourite tournament, where he is a record 10-time champion.

It is the sort of scenario he could only have dreamed about when learning to play the sport in Split, inspired by watching Novak Djokovic from afar.

But after so much good work in this set, the Croat falters from 30-0 on serve to concede a second successive break.

A big grin from Djokovic as his supporters welcome that with huge cheers. That's the first time we've seen that from the world number one tonight - and now he will serve for the set. Momentum shift.

From 3-2 down, Novak Djokovic battles back to 4-3 in an engrossing third set.

It has become quite the first-round treat for those lucky enough to be inside Rod Laver Arena - and who knows which way it will swing next?

Image source, Getty Images

Novak Djokovic eats high-pressure points for breakfast.

He washes the second break point down with an ace.

A big opportunity missed for Dino Prizmic, but the top seed isn't out of trouble yet...

Image source, EPA

Not so fast. Dino Prizmic dusts himself down and sets about attacking the Djokovic serve once again.

The qualifier moves 0-30 up before a miss from the world number one hands over two break points! It's turning out to be quite the rollercoaster, this.

That could be a significant moment in this match.

Novak Djokovic halts the run of games against him to restore parity in the third set and lave the match delicately poised.

He has a quick grumble to the chair umpire about more spectators filtering in. Will Djokovic push on from here?