And Grigor Dimitrov has wasted the chance to win the fourth set! The Bulgarian crumbles quicker than freshly-baked cookie, giving Murray three vital break points. And he takes one as Dimitrov commits the cardinal sin of an unforced error with the forehand! Now Murray serves to survive....

The fourth set is still in the hands of Grigor Dimitrov - he serves to draw level....

Goran Ivanisevic
2001 Wimbledon champion on BBC Radio 5 live

"When you are serving for the set you should always concentrate on the first point. That is the most important thing. If you win the first point then usually you win the game. That is what Dimitrov has to do."

Grigor Dimitrov threatens to tie up this set in Murray's own backyard, making deep incisions in the Briton's defence with some booming backhands. And ferocious forehands.

Murray is apoplectic with self-inflicted rage as Dimitrov forces a set point at 40-40. That goes begging before Murray argues with the umpire on the next point. The ball is called out, umpire says it was in, Murray responds with a jibe of "you're having a shocking day at the office'. Guess what? The umpire is spot on.

Murray puts his game head back on and serves out to win. Just.

DONG! The clock strikes midnight over in Melbourne - but this night is far from over. Andy Murray serving to stay in this fourth set...

Grigor Dimitrov appears to be having some racquet trouble, twiddling with his strings after going 30-15 ahead. Murray plucks an inch-perfect lob out of the top drawer, which Dimitrov scan only slam back into the net for 30-30.

The Bulgarian legs it over to his chair for a fresh racquet, before seeing another sublime Murray bomb loop over his head for 40-40. However, Dimitrov decides that is enough of that, bombing down two thunderous serves to hold.

Don't make him angry. Because that's when Andy Murray seems to be at his best - certainly in this match. The Scot goes on the attack, aggressively meeting a Dimitrov drop shot and then a forehand on his way to holding to love.

The fitness of these two guys continues to astound me. Every seemingly closed alley is closed off, perfectly illustrated as Murray busts a gut to reach a shot backhand from Dimitrov and scoop over the winner at 15-15.

But that's as good as things get for Murray, the Bulgarian taking charge to hold. Murray is angry about something, muttering loudly as he swipes a towel from the ball-girl's hand.

David Law
BBC Radio 5 live commentator

"Andy Murray is looking a bit perturbed with the way things are going, which is hardly surprising when you look at the scoreboard."

Image source, AFP

Andy Murray is wearing the expression of someone rather bemused by Grigor Dimitrov's resistance. The Bulgarian grabs a huge slice of luck in the first point, his backhand almost fully smashing the net cord before flipping over on to Murray's side.

However, Murray puts that behind him to dig in. At game point, a big serve is too hot for the Dimitrov forehand to handle and the Briton sees his side of the scoreboard tick into action.

Confident play from Grigor Dimitrov as he builds on the break with a service hold to love. Textbook.

Any way back for Murray? Or are we heading on the one-way road to a fifth set?

Andy Murray's serve and volley puts him back to 30-30 before another lengthy rally ends in Dimitrov almost doing the 'splits' in a failed attempt to stop Murray nudging himself ahead.

Is the Bulgarian limping after that? If he is, then the niggle soon disappears as he goes to advantage.

Murray moves close on the net, maybe too close, as he palms Dimitrov's big backhand into the net. First break of the third set goes to Dimitrov.

Andy Murray, like all Grand Slam winners, is smelling blood now. The Briton nicks another break point as the pair trade hefty blows, but he can't take advantage as Dimitrov survives.

The Bulgarian does more than survive that point though, going on to win a marathon 10-minute game.

Karan Nightingale:, external Come on Andy...have jobs to do this morning and I'm getting none done.

Andrew Priestley:, external Fantastic battling spirit from both of these players. Neither man giving the other an inch. Victory will have to be earned.

Goran Ivanisevic
2001 Wimbledon champion on BBC Radio 5 live sports extra

"The Australian Open is the fastest Grand Slam surface by far. That's why I always say it's the best tennis here as everyone goes for their shots."

Image source, AFP

And Andy Murray makes no mistake to take the third set. Smart serving by the 27-year-old leaves Dimitrov scrabbling about at the baseline as he springs forward to win this vital set. A long clench of the fist - and a steely stare - greets the winning point. He's happy.

Andy Murray serving for the third set and a 2-1 lead....

The temperature must be dropping in Melbourne, as Murray's fiancee Kim Sears seeks warmth by pulling her scarf around her face. I think she just wants to show off the rock on her finger to the cameras...

Anyway...the temperature on court is still sizzling hot. Murray moves within sight of the break at 40-15, but sees them swallowed up by Dimitrov's hefty serve. That's 10 of 14 break points that he's watched squirm out of his fingertips...

Then the Briton gets another chance at deuce. And he takes it! Dimitrov hammers into the net.

When the going gets tough, the Andy Murray serve gets going.

Grigor Dimitrov mixes up his range, with a couple of short cross-court forehands leaving Murray floundering at 0-15 and then 15-30.

But two flat serves to Dimitrov's backhand cannot be returned with menace and the British number one sees out a crucial hold.

What do you need at this stage of a Grand Slam last-16 tie? A comfortable hold. And that's what Grigor Dimitrov does. The Bulgarian pins back Murray - pressure back on the Briton.