Big hold for Sousa, who wins the game from 0-30 down.

Piers Newbery
BBC Sport at Melbourne Park

"It's breezy to say the least on Hisense but Murray is well used to that and got a handle on conditions after feeling his way for a game or two.

"This court is non-ticketed for the first time, due to the shiny new Margaret Court Arena, meaning big queues and lots of coming and going at the changeovers as those with ground passes get to check out a Wimbledon champion (and the Portuguese number one). It's like People's Sunday every day on Hisense."

Four-time Australian Open Roger Federer is up against it on Rod Laver Arena as Andrea Seppi breaks in ninth game of the second set and will now serve for a two sets to love lead. Remarkable scenes.

Piers Newbery
BBC Sport at Melbourne Park

Image source, EPA

"Seventh seed Tomas Berdych is safely through to the last 16 after a 6-4 6-3 6-4 win over Viktor Troicki on Rod Laver Arena. Watching from courtside was Dani Vallverdu, the Venezuelan coach who left Team Murray for Team Berdych in the off-season.

"I'm getting to a stage of my career, if I want to go forward and do better it's the right time to make some changes," Berdych told BBC Sport. 'I ended up with Dani, which is a great choice. I'm really happy with all the experience he has from the past, working with Ivan and being part of the team with Andy Murray. It's very helpful.'"

Image source, AP

It's all Murray at the moment, Sousa struggling to deal with the Scot's power as he is dragged from one side of the baseline to the other.

It's brutal hitting from Murray. Just brutal. The world number six mops up the game for the loss of just two points and the first set is his in a little of half an hour.

Murray goes big at 15-15, launching a fizzing forehand down the line but he's shaking his head before it's even landed. But it's that aggression which is putting Murray in the box seat.

The Briton keeps the ball in court in the next two points to bring up break point. Sousa then hits wide and Murray breaks. He'll now serve for the set.

Is Andy Murray a leading Australian Open contender? Let us know your idea of the winner by using #bbctennis, external posting on our Facebook page, external or by texting 81111.

Pratik Tarafdar:, external "May be not this time around. Federer, Djokovic, Raonic & Wawrinka are playing brilliantly. Then you also have Nadal."

Although Federer is currently a set down against Italian Andreas Seppi.

Sousa has not let his head drop after that break and bravely comes forward when given the opportunity to force deuce as Murray's serve continues to stutter. But the Scot comes through once more to win his third successive game.

Murray nails a trademark backhand down the line to haul himself back to 30-30 on the Sousa serve.

The Portuguese then throws in a slow second serve and Murray takes advantage, rattling a forehand cross-court and then sending another sizzler of a backhand down the line to bring up his first break point of the match.

A great change of pace, following up a looping forehand with a flat and heavy backhand winner to seal the game. "Come on," roars the Scot.

Image source, Getty Images

It's been a morning of mixed fortunes for Great Britain on the doubles front. Britain's Jamie Murray and Australia's John Peers, the 16th seeds, beat Australian duo Omar Jasika and John-Patrick Smith 6-2 6-3 in round two.

GB's Dominic Inglot and Romania's Florin Mergea, the 14th seeds, beat Argentina's Diego Schwartzman and Horacio Zeballos 7-6 (8-6) 4-6 6-2.

However, Britain's Heather Watson couldn't continue that success as she and Russian Alexandra Panova (pictured) lost 6-0 6-2 to Russian 12th seeds Anastasia Pavlyuchenkova and Alla Kudryavtseva.

Murray follows up an ace with his first double fault of the match to allow Sousa back to 30-30. The Scot then finds himself facing a break point after Sousa latches onto a pretty tame second serve. Fear not, though, as Murray's first serve comes to the rescue for deuce.

It's all a bit erratic from the world number six at the moment, interchanging aces with double faults. But he conjures up two successive big serves to get him out of trouble.

So far so good for Joao Sousa, the world number 55 racing to 40-0 without doing anything spectacular. Murray gets a point on the board, but the Scot's backhand then lets him down and it's one apiece.

Image source, Getty Images

Murray cruises through the opening game, the Scot sending a bullet of a serve down the middle to close it out to 15.

Joao Sousa wins the toss and elects to receive. Let's do this.

We've got a two-pronged attack on coverage for this match with David Law and the team providing online-only audio coverage. Just click the Live Coverage tab at the top of the page and hit play. Easy.

Roger Federer is in a spot of bother over on Rod Laver Arena, the four-time champion losing the first set 6-4 against Andrea Seppi. I'll keep you up to date on the progress of that match, but for now we return to the Hisense Arena where Murray and Sousa are reaching the end of their warm-up.

Andy Murray slaps on the suncream, fits his cap and heads out to begin the warm-up. It's another beautifully sunny day in Melbourne, but at 22C not the hottest conditions we've seen this week.

Do you agree with Goran Ivanisevic? Did Andy Murray make the wrong decision by splitting with Ivan Lendl? Everyone is entitled to their opinion, so let's hear yours using #bbctennis, external on Twitter, posting on our Facebook page, external or by texting 81111.

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Andy Murray has not reached a Grand Slam final since he won Wimbledon in 2013. Former Wimbledon champion Goran Ivanisevic has some thoughts on why his form has tailed off.

"He changed coaches," Ivanisevic told BBC Radio 5 live. "For me honestly that is maybe his biggest mistake, letting Ivan (Lendl) go, because it was a perfect match.

"They did everything well together, they won two Grand Slams, he played the best tennis under Ivan.

"They are similar tennis players but Andy is like Rafa (Nadal), a great competitor, a great tennis player. What he played last year, that was way off the standard of Andy Murray - overall it was medium, medium rare."

If Murray wins today, he will join Mats Wilander in 10th place on the list for the most Australian Open wins in the Open Era. However, that total of 36 would be 29 short of four-time champion Roger Federer's tally.