A super quick regrip of the racquet for Cameron Norrie at the change of ends.

Can he do mine after this match please? I'm mesmerised by how quick that was.

Image source, Getty Images

Cameron Norrie gets the hold!

Emilio Nava has the Brit firmly on the back foot and running left to right on the court, but nets a straightforward smash.

He had the break set up perfectly and a lapse in concentration costs him.

These two are in yet another tussle at deuce.

They have been on court for two hours and 55 minutes now, but neither player is willing to back down easily.

Emilio Nava thumps a forehand winner straight down the court but nets his backhand for the break.

On we go...

Image source, Getty Images

Alexandre strikes back against Alexander!

French world number 52 Alexandre Muller has taken the second set against German third seed Alexander Zverev and we're all-square on John Cain Arena.

Zverev had led the set 3-0 but Muller put together an excellent five-game streak to turn it around.

Muller had to survive a break point as he served for the set, and he managed to do just that at the first opportunity.

It could be Cameron Norrie, who is currently trailing 0-40 in his service game.

The American has three break points here. If he breaks, he will serve for this fourth set. The pressure is on.

And another service game sealed with an ace by Emilio Nava!

The American has hit an impressive 18 aces in this second-round match.

Who is going to be the first to blink?

Another game on the board for Cameron Norrie in this fourth set.

The Brit powers through yet another service game to hold to love.

His first serves are currently averaging 192km/h (119mph) - speedy!

Image source, Reuters

Mirra Andreeva speaking after her second-round win over Maria Sakkari: "When I saw the draw I was like 'wow'. It's not the easiest draw you can have because Donna [Vekic] and Maria [Sakkari] are both amazing players, such experienced players and they play aggressive tennis.

"It helps to be nervous earlier. When I saw the draw I was like OK, here we go.

"I think it helps to be 100% since the first match that you are playing because obviously you want to have some time to get into the tournament, but here I didn't have the time to do that. I needed to start 100% right away."

On winning Adelaide and knowing that many winners at Adelaide have gone on to win Australian Open: "Of course having a great week of playing before starting the first Slam of the year helps a lot, gives a lot of confidence. I was feeling great on the court.

"I know the statistic that winners of Adelaide do not bad here in Melbourne. But I'm not going to think about it, I'm going to take it match by match and then see if that statistic works for me."

Cameron Norrie is being vocal, but Emilio Nava is matching him and then some!

The world number 89 gets an important service hold hitting a forehand cross-court winner at full-stretch after being forced to deuce.

There was an opportunity there for Norrie, but he couldn't capitalise.

Image source, Reuters

Cameron Norrie posts his reply with a service hold of his own to 15.

The 26th seed is pumped up on court seven, he lets out an 'Allez!' to let everyone know how good he's feeling.

The pair are going toe-to-toe in this fourth set.

Emilio Nava seals his latest service hold with a superb ace out wide.

Cameron Norrie didn't even attempt to reach that one, it was that good.

He holds at 40-15 and asks the question of his opponent.

Image source, Getty Images

Home favourite Alex de Minaur has a battle on his hands over in the night session match on Rod Laver Arena.

The men's sixth seed has just lost an hour-long first set in a tie-break against the 90th-ranked Serbian Hamad Medjedovic.

After neither player could force a break point in the opening 12 games, Medjedovic dominated in the tie-break and took 4-1 and 6-2 leads before clinching his fourth set point to silence the Australian support.

The British number two races to a service hold to love after missing out on break point.

Let's see who's going to blink first in this fourth set...

No, he won't.

Cameron Norrie forces Emilio Nava all the way to deuce on his opening service game, but he rises to the occasion and hits a backhand winner straight down the court to hold.

The crowd is naturally behind the Brit, who grew up in Auckland, so the American is having to be his own hype man. Luckily, he is full of passion.

Image source, EPA

The expressions on each of the players faces at the end of that eighth game told a story.

Maria Sakkari gave a wry smile as her forehand smacked into the net - wrapping up the hold for Andreeva, who let out a furious shout of 'come on'. She's not having it all her own way now.

But the Russian teenager carries that anger into the next game and overpowers Sakkari with some huge forehand hits to break.

She'll serve for the match now.

Will Cameron Norrie get an early break here?

He has opened up a 0-40 lead on Emilio Nava's serve, forcing error after error from the American.

A great start to this fourth set by Cameron Norrie.

He takes a 40-15 service hold with some huge serves and some powerful hitting down the court. He is definitely trying to make an impression.

After all, he is the final Brit in the men's singles draw after Arthur Fery's straight-set defeat by Tomas Etcheverry earlier today.

Daniel Kiernan
Former British tennis player on BBC Radio 5 Sports Extra 2

It was a great set of tennis from Nava.

He served at 76%, won 77% of his first serves and 71% of his second serves.

We talked about 'going big or going home' and he very much did that.

We know Cameron Norrie loves a battle and he is in one right now.