Big, big hitting from Coco Gauff and eventually Leylah Fernandez misses.

The third seed has the chance to restore her double break.

Novak Djokovic has got the trainer out at the change of ends.

Something has definitely been bothering him in this second set.

Just as we thought Coco Gauff was strolling her way to victory, she falters. Two rare double faults and Leylah Fernandez narrows the gap.

Gauff still has the cushion of a single break, though.

Ryan Harrison
Former American tennis player on BBC Radio 5 Live and BBC Sounds

Image source, Getty Images

Machac is going full lockdown mode on these rallies.

He is playing aggressively and the second that he notices Djokovic is outside of the court, he sneaks in and puts that volley away.

You just get the sense that this is starting to turn a bit...

Got it!

Andy Murray is on his feet in Novak Djokovic's coaching pod as the Serb puts us back on serve.

He looks pooped, to be honest, and places the towel over his head as he sits in his chair.

Hold on! Leylah Fernandez knows she needs to step things up if she is to have even a slither of hope in this match.

The Canadian aggressively dashes to the net to dink over a volley and a double fault - Gauff's first of the match - bring up two break points for Fernandez.

Here we go. Novak Djokovic still looks like he's struggling a bit out there but he fights back to bring up two break-back points.

Jack Draper better hurry his warm-up preparations. Coco Gauff pinches the baseline with a fine forehand and gets the double break.

She's absolutely flying here.

It just proves how important that hold was in Tomas Machac's opening service game.

The scoreboard now looks pretty good for him.

Brilliant from Thomas Mahac!

His movement has been very impressive throughout the match but he is now managing to find the winners to go with it. He slips and slides across the baseline then Djokovic's forehand drifts wide.

A reminder that Britain's Jack Draper is on Margaret Court Arena this one.

And it could be very soon indeed as Coco Gauff brings up three points for the chance to go a double break up.

Novak Djokovic was clearly pretty exhausted from that last game, is now Tomas Machac's chance to put some pressure on?

The Czech player certainly thinks so as he brings up two break points after yet another gruelling rally where Djokovic pushes into the net.

Ryan Harrison
Former American tennis player on BBC Radio 5 Live and BBC Sounds

It seems to me that Tomas Machac is sensing that there is something going on over on the other side of the net.

He doesn't know what it is exactly but that will give him a really big sense of belief, especially after the first set where it was so one-sided.

Leylah Fernandez almost looks close to tears. She's having no luck at all on Coco Gauff's first serve and she can't deal with that lovely little volley before Gauff sends an ace down.

A very easy hold for the American.

Finally, Tomas Machac gets the hold over the line after a physically tough game where he had to save two break points.

Novak Djokovic was bent over leaning on his racquet at times in that game, clearly tiring work out there.

Coco Gauff picks up where she left off, and it looks like this could all be over very quickly for Leylah Fernandez.

The Canadian plants the ball into the fence and concedes serve.

Break point saved again as Novak Djokovic thinks Tomas Machac's shot is going wide and opts to leave it but it kisses the line.

Machac has a third game point thanks to a big serve, can he get it over the line?

Tomas Machac saves break point after another lengthy rally. He moves into the net and sends the ball into the space behind Novak Djokovic.

Some huge rallies here and both men are having to really work for it.

Another one at deuce hands Djokovic a second break point as Machac fires wide.

A clenched fist and a puff of the cheeks from Coco Gauff as she wraps up the first set after 44 minutes.

She improved as the set went on, and Leylah Fernandez is going to have to be a lot stronger on serve if she's to have any chance of stopping the third seed.

Image source, Getty

Ryan Harrison
Former American tennis player on BBC Radio 5 Live and BBC Sounds

You want to make Coco Gauff have to serve this thing out.

At different stages of her career, we have seen that Coco has some double faults that have crept in, especially in these later stages of Grand Slams and in these high pressure matches.

So it is really important for Leylah Fernandez to find a hold and make Coco Gauff serve it out on serve, where she has struggled at times in the past.