That forehand from Stefanos Tsitsipas!

It comes flying down the line at Roger Federer and he blocks the ball back into the net, and the Greek holds to 15.

Federer will have to serve to stay in the set.

Jonathan Jurejko
BBC Sport at Melbourne Park

"Komm schon," is what I think Federer shouted on his way to that hold.

That's 'Come on' in German. Whatever he said, it was yelled with a mixture of relief and celebration.

This is FAR too tense for a Sunday morning.

Mark Woodforde
17-time Grand Slam doubles champion on BBC Radio 5 live sports extra

All the mistakes came from the Tsitsipas forehand side.

Huge yell from Federer as Tsitsipas, darting behind the baseline, misses a forehand.

And Tsitsipas nets another huge cross-court attempt!

We're still without a break of serve.

First serve down the T from Federer, and it's blocked into the net by Tsitsipas!

Deuce.

Oh, that should be the break for Stefanos Tsitsipas, but he misjudges his pass and Federer volleys the ball away!

30-40...

Well then!

Roger Federer finds himself 0-30 down, rescues a point with a big first serve, and then he's passed brilliantly by Stefanos Tsitsipas!

For the first time in the match, Tsitsipas has break points on the Federer serve...

Two hours and 36 minutes on the clock.

45 winners and 35 unforced errors from Federer.

46 winners and 28 unforced from Tsitsipas.

It's close.

Image source, Getty Images

Image source, Getty Images

Terrific one-two punch from Stefanos Tsitsipas, going out wide on serve then following it with a forehand winner.

And this time, Tsitsipas closes out as Federer blazes a forehand into the net!

There's no returning that serve.

Game point, Tsitsipas - but it goes begging thanks to a wayward forehand!

HOW has Federer made that?!

Tsitsipas leaps into a huge cross-court backhand, both feet off the floor and Federer, at full stretch, somehow manages to toe-end the ball past Tsitsipas and onto the line.

Deuce.

Made it!

That's a loose drop shot from Federer and Tsitsipas, grunting with effort, runs forward and passes Federer with a sweet backhand.

What a shot that is! Game point to Tsitsipas.

Yes. Yes it is.

Down the line goes Stefanos Tsitsipas, surprising Federer, and we're at deuce.

Image source, EPA

OH!

Federer somehow keeps defending his way back into a rally, he sets himself up for the forehand winner - and it's a horrible shank!

0/11 on break points. Is it going to be 0/12?

Stefanos Tsitsipas turns into Roadrunner to meet a Roger Federer drop shot, and Federer leaps to crack the inviting return past his opponent.

Now then! This is better from Federer, passing Tsitsipas at the net, and he's earned himself two break points.

If he lets these go...

Russell Fuller
BBC tennis correspondent at Melbourne Park

There's not been a single break of serve in this match. Federer has had 10 but not been able to make one of them. That's incredible.

Federer makes a mess of a serve and volley move, driving the ball over the tramlines for 15-30.

That's a better approach, Federer sliding into a volley for 40-30, and then a block at the net tidies up a hold.

It's not as easy as it might have been for Fed out there.

The "win predictor" is still heavily in Federer's favour, according to my TV screen.

I don't know what a win predictor actually is.

Image source, EPA

Russell Fuller
BBC tennis correspondent at Melbourne Park

I think this is a real fight for survival now for Roger Federer.