Before we focus on Emma Raducanu against Coco Gauff, let's get a bit more reaction to Rafael Nadal's exit this morning.

Image source, Getty Images

Just waking up? Here's a recap of what has already happened on day three in Melbourne:

• Rafael Nadal's title defence is over following a straight-set defeat by American Mackenzie McDonald in which he struggled with an injury;
• Women's top seed Iga Swiatek eased through in a 6-2 6-3 win against Camila Osorio;
• Third seed Jessica Pegula beat Aliaksandra Sasnovich 6-2 7-6 (7-5) and sixth seed Maria Sakkari avoided a shock as she fought back to beat Russian teenager Diana Shnaider 3-6 7-5 6-3.
• Petra Kvitova, the 15th seed, is out following a 7-5 6-4 loss to Anhelina Kalinina.
• In the men's draw, sixth seed Felix Auger Aliassime has come back from two sets down to defeat Alex Molcan 3-6 3-6 6-3 6-2 6-2.
• Italian 15th seed Jannik Sinner won 6-3 6-2 6-2 against Tomas Etcheverry, while American 16th seed Frances Tiafoe beat Shang Juncheng 6-4 6-4 6-1.

Welcome back!

Recovered from that early morning shock defeat for Rafael Nadal?

Good, because we've got another big match coming up.

Britain's Emma Raducanu and American teenager Coco Gauff will soon begin the night session on Rod Laver Arena.

We'll also get more reaction to that second round defeat for Nadal, in which he struggled with an injury.

BBC Radio 5 Sports Extra

While you continue to enjoy live radio coverage on Tennis Breakfast on Radio 5 Sports Extra, we're going to pause this live text for a little while before returning with build-up to Emma Raducanu's eagerly anticipated second-round match against Coco Gauff.

Back soon!

Russell Fuller
Tennis correspondent at Melbourne Park

There have been times when Rafael Nadal has pulled out of Grand Slam matches - today he felt he could continue with no further problems.

He was barely moving, but serving quite nicely, but once he was broken it was all over.

We have to say how well Mackenzie McDonald played. He absolutely made all the running in the early stages. Nadal was clinging on.

I don't know if that was a pre-existing condition - we'll find out more when he gives his press conference.

Image source, Getty Images

So far today, women's top seed Iga Swiatek has already eased through, winning 6-2 6-3 against Camila Osorio.

Third seed Jessica Pegula beat Aliaksandra Sasnovich 6-2 7-6 (7-5) and sixth seed Maria Sakkari avoided a shock as she fought back to beat Russian teenager Diana Shnaider 3-6 7-5 6-3.

Petra Kvitova, the 15th seed, is out following a 7-5 6-4 loss to Anhelina Kalinina.

In the men's draw, sixth seed Felix Auger Aliassime has come back from two sets down to defeat Alex Molcan 3-6 3-6 6-3 6-2 6-2.

And Italian 15th seed Jannik Sinner won 6-3 6-2 6-2 against Tomas Etcheverry.

BBC Radio 5 Sports Extra

A reminder that you can tune in to Tennis Breakfast from 7am on Radio 5 Sports Extra.

You can listen on BBC Sounds or simply by clicking on the icon at the top of this page.

Plenty more day three action to come, along with reaction to Rafael Nadal's early Australian Open exit.

How significant was this wave to the Australian Open crowd from Rafael Nadal?

Those in Rod Laver Arena rose to applaud the two-time champion off the court as he took his time to thank the crowd before exiting.

Image source, Getty Images

Image source, Getty Images

Jonathan Jurejko
BBC Sport at Melbourne Park

Good news! The rain has stopped at Melbourne Park and the players are out on the outdoor courts.

As well as the second-round matches, there are still several first-round contests which need to be finished after being held over from yesterday.

Andy Murray is still waiting to find out his next opponent with Australia's Thanasi Kokkinakis and Italian veteran Fabio Fognini yet to be concluded.

That one might not take too long with Kokkinakis just two games away from victory.

It does once again raise the question of how long Rafael Nadal can go on for as the injuries continue to affect him.

He was forced to withdraw from his Wimbledon semi-final against Nick Kyrgios last summer with an abdominal injury.

That came a month after he won his 14th French Open title without being able to feel his left foot as it was anesthetised because of a chronic condition.

We will have to wait and see how serious this issue is.

Mackenzie McDonald still played a great game and was almost two sets up before Rafael Nadal pulled up with his injury.

It's the biggest win of his career and he did well to maintain his focus and see that victory out in difficult circumstances.

Jonathan Jurejko
BBC Sport at Melbourne Park

It's a long, lonely walk up the 'Champions' Walk' from the court to the locker room and we've just seen Nadal trudge slowly back up the carpeted corridor.

Tennis can be a cruel sport sometimes.

Winner Mackenzie McDonald, speaking in his on-court interview, says of Rafael Nadal:

"He's an incredible champion.

"He's never going to give up so closing it out against a guy like that is tough.

"I'm happy I kept focusing on myself and got through."

Jonathan Jurejko
BBC Sport at Melbourne Park

Rafael Nadal looks like he is glad that ordeal is over.

A subdued and respectful reaction from Mackenzie McDonald, who must be dying to break out in a beaming smile.

Nadal makes a slow walk off court and waves an emotional goodbye.

He hopes he will be back. So do too the Australian fans.

But you never know...

Let's hope that injury isn't too serious for Rafael Nadal, who was clearly struggling physically since he first pulled up with what appeared to be a hip problem towards the end of the second set.

He receives a great reception as he waves goodbye to the crowd at Rod Laver Arena.

Nadal fights back with a forehand winner.

But McDonald will have two match points.

The occasion isn't getting to Mackenzie McDonald here.

And Rafael Nadal is beginning to look like a beaten man.

McDonald moves two points from victory with a forehand winner.

Nadal's title defence is hanging by a thread.