Tick tock. The clock ticks past the two-hour mark as Djokovic tosses up to stay in the second set....

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"The break after the protesters helped Andy Murray more than Novak Djokovic, who now has to come up and hold his serve. But the way Murray is pumped up, it won't be easy and it means Djokovic has to come up with a good game."

Image source, AP

Aussie actor Eric Bana is best known for his role as the Incredible Hulk - a character which Andy Murray resembles now and again on court. Without the green body paint of course.

But the Scot is pretty calm at the moment, and for good reason. This game has had more gear changes than a battered Vauxhall Nova and now it is Murray who is coasting along in fifth. An impressive service game - a hold to love - puts the British number one in the driving seat.

After that brief interlude, we're back under way. The respite does Murray the power of good, the Briton snatching the first point with a peach of a forehand.

Djokovic jabs back at 15-15 before another stinging Murray return catches Djokovic off-balance. These long-standing rivals trade blows again, Murray moving within sight of a break when a baseline rally ends in Djokovic finding the net with a stretching forehand.

Break point for Murray - and the British number one is back in business! He decides to bring another slugfest to an end with a sweeping forehand down the line.

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"It's a pretty good effort to get on to the court as you have a 15-foot jump down to the court, so I don't know how they got down there. The two people had a banner of some sort that they did not have time to unveil before they were escorted away.

"There are 14 security guys there and four of those men were standing around and protecting each player."

Image source, Getty Images

Idiot alert. A couple of spectators have dodged security and managed to run on to Rod Laver Arena to voice some sort of protest. A host of burly yellow-shirted security guards quickly spring into action, keeping the culprits away from the players and then turfing them out to cheers from the other fans. There's always someone wanting to spoil the fun....

"Come on. Come on!" is the pep talk that Murray gives to himself after Djokovic tries to get inside his head. The Serb questions a clearly good Murray forehand return at 15-15, Murray grinning as he gets the nod from the computer.

Murray crunches another winner to go 40-15 ahead, before an aggressive Djokovic has a go back to win the next point. Murray rises to the challenge though, spanking an ace down the T.

Image source, Jelena Djokoivc

Novak Djokovic's wife Jelena posts a picture on Twitter, external of their baby son watching the match on television and says: "Everything looks so much better from this perspective. In Stefan's world, daddy is always a winner."

Image source, Getty Images

Djokovic is finding more rhythm than a funk and soul band now. The Serb booms down serve after serve for a hold-to-love game. Easy. That's 12 straight points for the world number one - Murray must stop the rot. Quick.

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"This is what I didn't want Andy Murray to do - drop into just one pace. Unfortunately he has done that and Novak Djokovic clicks into rhythm well.

"When he's in that rhythm it's really hard to break it. Murray has to start mixing it up as it is like a warm-up at the moment.

"There's still a long way to go and Djokovic may go off the boil as he did in the first set, but the reality is he has been in a lot more tough match-play situations than Andy and that may make the difference."

Uh oh. Dangerous times for Murray. Djokovic ups the ante, slamming his foot on the returning pedal as Murray struggles to keep pace.

The Serb has three break points. Murray tries to pick at the Djokovic backhand. The response? A crashing return down the line. Murray aims to get Djokovic scampering across court but the Serb dashes to his right like a 100m sprinter to fire back a winner.

Dom Bourke:, external Murray needs to avoid getting embroiled in Djokovic's injury woes and play his own game. Needs to stay focused.

Daniel Simmonds:, external This match is like a watching a Korean movie in a hotel on a stopover. #confusing

Fissuh H Kelelom:, external Head says Novak, heart says Andy. Come on Andy you can do it with a bit of mental strength. Novak is mentally very strong.

Image source, Getty Images

This contest is getting a little X-rated. And Murray's fiancee Kim Sears has not even uttered an expletive. Instead it is her hubby-to-be - and his opponent - who are castigating themselves with naughty shouts and racquet slams.

And it isn't surprising as this game see-saws on the edge. Djokovic chips away at the Murray forehand, eventually levering himself into a 40-30 advantage. The Serb steps into the net and thumps a passing volley into the covers to move back level.

Image source, Caroline Stokes

Caroline Stokes shows her support for Andy Murray with this picture on Twitter., external

While Djokovic's ankle is not up to speed, the Serb's brain certainly is. Trailing 15-0, he outfoxes the Briton who is left panting after being forced to chase the ball all over the court.

A backhand error into the net gives Djokovic a sniff of the break at 30-15, then a huge whiff drifts under his nose as a cross-court dropshot puts him 40-30 ahead.

And he snaffles that chance like a hungry fox to break back instantly. Murray drills a forehand into the net. Djokovic's ankle injury suddenly appears to have disappeared....

Pat Cash
1987 Wimbledon champion on BBC Radio 5 live

"It is now time for Andy Murray to put the pressure on and he has been gifted a couple of shots by a partially-lame Novak Djokovic."

Image source, Australian Open

Now I'm no physio - but I have had a few ankle injuries in my time. And Djokovic seems to be struggling - especially when he loses a point...

Djokovic drills a poor forehand into the net to give Murray two break points. The Briton needs just the one! The Serb plants a baseline backhand into the tape as Murray whoops with joy.

Russell Fuller
BBC tennis correspondent

"Djokovic with the first set, but very little between them. Both give the impression they have prepared themselves mentally for a long night."

Image source, Getty Images

Back to business. Murray needs to make a flying start - and he does. A dropshot looks too short for Djokovic, who stretches to put racquet to ball, but can't find the court.

The pair trade points before Djokovic goes long to leave Murray on the verge. More worryingly for the Serb, he takes tumble after that return, crumbling to the court like a soggy digestive biscuit. Looks like a left ankle problem to me.

He gingerly climbs to his feet, but can't reply to a booming Murray serve. Easy hold for the Briton. Djokovic with a slight limp as he makes his way back to his seat.