Murray looks every bit the predator toying with his prey now. He sends a couple of drop shots over the net and the second is unreachable as Nava falls 0-15 down on his serve.

Nava hits the ball out, then into the net and he faces three break points.

David Law
Commentator on BBC Radio 5 Live

Nava is actually starting to fall away a little bit here. And Murray is beginning to sense it.

Nava is doing his best to stay in each point, recognising that if he stays a break down here coming back against Andy Murray is not going to be easy.

But Murray's level is unreachable right now. Nava comes to the net and he hits a superb backhand winner down the line.

The Brit makes life a bit easier for himself on the next point, with a solid serve to hold.

Naomi Broady
British player on BBC Radio 5 Live

It is exciting for Nava to know he can play that level of tennis, but it is a lot to do it at a Grand Slam. That is why the top three have been at the top for so long. Murray knows what it takes - the frustration that he would have to take it in four at least.

Murray is now just dialled in. He's just business-like and has the belief that Nava cannot reproduce that form of the first set.

The first break point is saved as Nava comes to the net and slaps down a winner.

Then, another entertaining one. Murray is forced to twist and hit a backhand overheard in the air as Nava goes for a lob. A lot more running this way and that ensues, but it is Murray who comes out on top.

Nava was superb in the first set, but he has not quite matched Murray's level since.

Murray fails to return a serve and bats his racquet with his hand in agitation.

Then, an excellent rally as Murray comes forwards to pick up a ball that clipped the net cord, hitting a solid backhand down the line.

The Brit follows that up with a drop shot and Nava goes long.

Well, well, well.

Nava sends a backhand into the net - a second error in a row - and finds himself 0-30 down on serve.

David Law
Commentator on BBC Radio 5 Live

Murray is trying to ramp himself up here because we are in the heart of this match. A bit of inspiration and he could really start turning this in his favour.

Murray channels that frustration into an ace for his hold.

Emilio Nava holds his head in his hands as he misses his passing shot with Murray at the end. What could have been 15-30 is instead 30-15.

Murray cuts a more frustrated figure, holding his hands out and questioning his box as a backhand goes into the net for 30-30. His coach Ivan Lendl isn't there at the moment, which might be why the Brit dared to do that.

Murray sends a couple of wildcards Nava's way: first a short return, then a lob. The American smashes the second down to go 30-15 up.

A 129mph serve gets him his hold. The 20-year-old is not giving up yet. This is going to be an exhausting match for them both.

David Law
Commentator on BBC Radio 5 Live

We might see Murray slightly break Nava's heart. If Nava is hitting his good stuff and Murray is hitting back right at his feet, the belief may sap, and he may feel the tiredness from his five-set first-round.

Wow. Emilio Nava looks like he's whipped a forehand winner on the angle but Andy Murray sprints to get to it and claims the point himself.

Overall, it's a quick hold to kick off the third set.

Naomi Broady
British player on BBC Radio 5 Live

Murray is being so much more aggressive in the second set. He is definitely hitting the ball harder - and he has had to because Nava was just eating those shots up.

He needs to keep that aggression up now. He will keep trying to ask the question to Nava - can you sustain your level from the first set, because if not - I am going to beat you.

Into the net again!

Andy Murray is back in this.

Here we go. Nava finds the net, Murray finds his chance.

That will help Murray's endeavours.

Nava kicks off his service game with a double fault.

But the former world number one can't return the next serve and it's 15-15.

A bit of back and forth ends when Murray whips a winning forehand into the corner for 15-30. Two points from claiming this set.

Andy Murray is looking to reach the third round of a Grand Slam for the first time in over a year.

He'll have to take a slightly longer route if he is to get through this match, but things are looking good in this second set as he gets a comfortable hold for a 5-3 lead.

Naomi Broady
British player on BBC Radio 5 Live

Players have always been able to yell at the box, but before the introduction of coaching they were never allowed to speak back and I think the organisers don't want the optic of a long coaching discussion at the side of the court.

But players won't want to be stood there having a conversation either. They will want to be getting on with things.

The clock hits two hours and we're still in the second set.

Murray is serving in the sun now and he throws the ball up a couple of times to test when it might disappear into the light.

He gets his first serve away alright despite the challenge, but on the next point bats a backhand into the net for 15-15.