That'll do nicely for the Greek, he holds to love to settle any nerves.

A leaping second serve from Stefanos Tsitsipas and Rafael Nadal can only tug it into the far tramlines. The Spaniard gets over the next to engineer it back towards his opponent but Tsitsipas finds his depth and fizzes his way to 40-0.

Andrew Castle
BBC Sport tennis commentator on BBC Radio 5 Live Sports Extra

I'm slightly concerned at this point that Tsitsipas is trying to come over every single backhand that Nadal throws to him. There are three errors on that side and the game concludes with another error on that side.

There are whole matches where no-one gets out of that side when Nadal pins you back there. How you break that pattern is a key part of the match for me.

Rafael Nadal rattles off a couple of quick points after that double fault to hold and get on the board in the quarter-final.

Nadal in luminous orange, Tsitsipas in high-vis jacket yellowy green - it's like a baby sensory class with my six-month-old on Rod Laver Arena. A rare double fault from the second seed for 30-30.

Gigi Salmon
BBC Radio 5 Live Sports Extra tennis commentator

Stefanos Tsitsipas has a strut about him, A tall guy, broad shoulders. He's pacing forwards not backwards.

Good start for Stefanos Tsitsipas, winning the opening exchange as Rafael Nadal digs a backhand into the tape, but the Spaniard just cranks up his next serve a touch and that's 15-15.

Right then, it'll be Rafael Nadal to serve first.

Away we go.

Andrew Castle
BBC Sport tennis commentator on BBC Radio 5 Live Sports Extra

Stefanos Tsitsipas has had a few days without playing but it is better than having played for four hours in the match before facing Rafael Nadal.

Image source, BBC Sport

We're moments away from this one, which way do you see it going? Let us know at #bbctennis...

David Law
BBC Radio 5 Live Sports Extra tennis commentator

I do feel the fact Tsitsipas has got to beat Nadal, Medvedev and probably Djokovic to win the Australian Open means he probably won't. It is brutal.

Russell Fuller
BBC tennis correspondent on BBC Radio 5 Live Sports Extra

This could be the year which Tsitsipas finally wins his first Grand Slam. I'm not convinced it will be here but he has certainly got the potential.

Would anyone would gobsmacked if on Monday we are reflecting on Tsitsipas joining the Grand Slam winners' circle? I don't think so.

Rafael Nadal, the 2009 winner and number two seed, gained a routine 6-3 6-4 6-2 win over Italy's 16th seed Fabio Fognini to progress.

But it was Stefanos Tsitsipas who enjoyed the least-taxing route through the last-16 matches, with the Greek fifth seed handed a walkover win after Matteo Berrettini of Italy had to withdraw because of an abdominal injury.

Enjoying Stefanos Tsitsipas' face mask as he waits to head out, which appears to have a cartoon/emoji-like picture of himself on...

Andrew Castle
BBC Sport tennis commentator on BBC Radio 5 Live Sports Extra

Every match-up is a good match-up for Daniil Medvedev at the moment. He is the form horse here. He might be the player we expect to win the men's singles.

He's unbeaten in 19 matches and has beaten 11 top-10 players since the US Open.

That's phenomenal and a moment of arrival for Medvedev.

You know the drill. Click the tab on this page to listen to our radio colleagues. And keep reading along here too!

Image source, Getty Images

In 1956, Stefanos Tsitsipas' maternal grandfather Sergei Salnikov became an Olympic champion in Melbourne, playing as a striker for the Soviet Union's football team.

Some 65 years later, the 22-year-old Greek grandson he never met is chasing his first Grand Slam victory in that same city.

Family means a lot for Tsitsipas. And so does the Australian Open - this was where he first announced his sporting potential by defeating his idol Roger Federer on his way to the 2019 semi-finals.

Since then, he has won four ATP titles, including the ATP Finals of 2019, and is currently ranked sixth in the world.

Already seen as a natural heir to the current generation's dominant figures, he is exciting to watch, and a charismatic, refreshing presence on and off the court. But there is another, perhaps unexpected side to him...

You can read Alexandros Kottis' excellent piece on the Greek here to delve into Tsitsipas' world.

Rafael Nadal did not play in the tournament-preceding ATP Cup because of a back injury, and that has meant him altering his service motion in Melbourne, though he is yet to drop a set and has held in 52 of his 56 service games.

“I think I had an amazing preparation for the tournament," said Nadal. "I practised very well in Mallorca and the first week in Adelaide had been fantastic, then what happened with the back, of course that stopped me a lot.

"But I was able to win the four matches already here, so now I'm going to have a very tough opponent in front,” he said.

“I need to play my best. Let's see if I am able to do it.

“I'm excited about playing that quarter-finals match. If we compare how I was five days ago and how I am today's situation, it's different, and my perspective and excitement is completely different, too.”

Image source, EPA

With 20 Grand Slam titles already crowding his mantelpiece, Rafael Nadal was asked what it is that keeps bringing him back to play more tennis...

"I play tennis. I like tennis. I like what I am doing," he said. "That's the main thing. I mean, of course I am very motivated to win Grand Slams and to play in the most important events of the year. No doubt about that.

"The only thing that I said is I have never been obsessed to try to be the best, no, I just did my way. That worked for me.

"I think the ambition is important, to have an ambition, but a healthy ambition. If you have too much ambition then you can be frustrated when you are not able to achieve all the things that you wanted. I never approached the sport and my career that way. That's it.

"I enjoy, I give my best always. I try to compete at my highest standards every day. Sometimes the highest standards are 60%, sometimes they are 100%. But I just try to give my best throughout my career, and that's it.

"For me the main thing is come back home with personal satisfaction that you gave it everything."