The start of the end?

Andy Murray looks like he has sniffed the stable. The Scot is straining for home and snaps Sousa's serve over his knee to give himself an immediate advantage in the fourth.

BBC Radio 5 live sports extra

American doubles specialist Eric Butorac: "Andy is going to be very pleased with how he took the set, he played some beautiful tennis."

A vicious ace - crumpling Joao Sousa's racquet and twanging the Portuguese's wrist tendons - completes an scrappy third set for Andy Murray.

Never mind what it looked like though. It is safely stored in Murray's racquet bag and means that Joao Sousa needs to find his best tennis for two whole sets.

He has been good, but has not convinced that he is capable of such consistency just yet.

Image source, AFP

Heather Watson is fighting to get back into her match but is isn't having much joy. She is a break and set down to American Sloane Stephens on court seven, and running out of time.

Well, that is just lovely.

Joao Sousa strikes a 100% proof backhand down the line to set up game point from deuce. Hardly a whisper off the racquet as the Portuguese found the sickly centre of the sweet spot.

Murray is pulled out of shape in the following rally and he will have to serve out to win this third set.

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Novak Djokovic comes through his second-round match and an injury scare to his back with a stylish win.

The world number one beat Luxembourg's Gilles Muller 6-1 6-4 6-4 as he continues his push for a first French Open title.

The engine is not exactly purring, but Andy Murray is at least making progress - rather than being stuck in reverse as he was for the second half of the second set and the first half of the third.

He backs up with his break with a hold.

If Murray goes on to win this one it will be among his uglier victories. But all that matters is the ticket to the third round.

An instinctive flicked backhand volley at the net after Joao Sousa had scooped one up from the dust helps Murray towards break point at 30-40,

Sousa is looking twitchy. He is shuffling a little awkwardly between points. Murray gets really stuck into the vital point, Sousa playing catch-up tennis throughout the rally, before finally he is out of control and can only fend a hurtling forehand long.

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American doubles specialist Eric Butorac: "That was exactly what Murray needed, to set the tone with a quick hold. Hopefully he can sink his teeth in now."

Joao Sousa has been nipping around Andy Murray's ankles like a terrier, but the British number one has given his opponent the slip there.

A hold to love. Is that a launchpad to stage the comeback? Time to turn the magnifying glass back on the Sousa serve and see how sturdy it really is.

Image source, AFP

Joao Sousa is going anywhere. He's as stubborn as grass stains in Wimbledon whites.

He battles on from deuce to hold serve and looks like he is enjoying the scrap.

Why shouldn't he? All to gain for the 26-year-old world number 44. All to lose for Murray.

Andy Murray is fire-fighting now.

He dumps a big bucket of ace on a second break point for Sousa after the Portuguese has slapped away a smash at deuce.

Sousa is crawling all over his groundstrokes and errors are pock-marking the Murray game.

Murray pumps three big gleeful jabs down at the clay as he puts away a backhand volley for advantage.

He looks like he would like to do something similar to umpire Pascal Maria as he loses his first serve to a time violation on game point.

Murray claims that there was some movement in the crowd that was putting him off. He puts away the point behind his second serve anyway and howls back to his box in celebration.

Piers Newbery
BBC Sport at Roland Garros

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"It's hard going so far for Heather Watson on Court Seven. After a lengthy study of a mark, umpire Carlos Bernardes decides Sloane Stephens had hit the line with a rasping forehand and the first set is hers.

"Watson was 3-0 down after eight minutes and her 4-0 record against Stephens might be a bit misleading. The American has been through a few major slumps since making her breakthrough with victory over Serena Williams at the Australian Open a couple of years ago. She appears to be finding her form again."

BBC Radio 5 live sports extra

American doubles specialist Eric Butorac: "Sousa has done an excellent job of taking control of this match after a first set in which he was greatly outplayed. He is playing with passion and enthusiasm."

Heather Watson is struggling against Sloane Stephens out on court seven. She has dropped serve three times and trails 5-1 in the opening set. What can she do to get back into the match?

Joao Sousa rattles through a service holds to love.

The tables have pretty much spun 180 degrees from the start of the match when Murray was racing through service games and then subjecting Joao Sousa to a thorough interrogation every time it was his time to tee off.

Russell Fuller
BBC tennis correspondent on Radio 5 live sports extra

"Murray is getting pretty frustrated, he is not boiling over but he is upset with himself. What has been a serene three or four weeks shows signs of being derailed."

This is turning into a real slog.

Murray is reeled in from 40-0 to deuce by an increasingly buoyant Sousa.

The crowd are throwing their weight behind the Portuguese as well. They huff and puff over a line call against Sousa.

They like a bit of revolution in the French capital and things are getting a little 1789 on Murray's behind at the moment.

He keeps a lid on the uprising with a hold of serve.

Matt McGladrigan:, external Pretty poor from Murray in that set. Lost his focus, low first serve % and more errors. Sousa attacking more effectively though.

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Brows starting to furrow in Camp Murray.

Their man landed just 36% of his first serves in that second set.

Sousa is ahead on the scoreboard for the first time as he holds in the opening game of the third set.

Suddenly those 20-1 pre-match odds on a Sousa victory don't look like such a silly investment.