A tussle indeed in this ninth game. Djokovic saves game point at 40-30 with a perfectly planted forehand down the line but he's left frustrated as Couacaud earns the advantage.

The Frenchman fails to convert but then gets another shot as Djokovic fails to return a serve, the Serb then slams a backhand return into the net and it's a hold for Couacaud.

Huge roars around Rod Laver, while Djokovic is definitely in some discomfort.

David Law
Commentator on BBC Radio 5 Sports Extra

There are lot more extra steps from Djokovic, tip-toeing to the ball. It is quite disconcerting to watch. I don't think I have ever seen him having any issue in the legs because of his elasticity.

There is a weird look in his eye - and his body language is a bit disengaged.

Djokovic is definitely feeling his hamstring - a hop here, a stretch there.

But for Couacaud, what injury? At 40-0 down, his movement around the court is sensational to steal a point back at the net.

Yet Djokovic's dominance on serve continues, wrapping up the hold to 15. The crowd is sensing a real tussle here.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra

Couacaud seems to have got over his concern over his ankle.

You would never have picked Couacaud to come out of top of some of these longer rallies. He is outmanoeuvring Djokovic and that is not easy for anybody.

We are not seeing any emotion out of Djokovic at the moment. I think he is OK on the take-off or not at a stretch. It is more lunging for serves or being defensive on the rally ball.

Couacaud races into a 30-0 lead but concedes a point as he smashes a backhand into the net. From there, he earns himself two game points with an ace, but drops both opportunities, his shot selection not quite right.

Couacaud cancels out a Djokovic break point with another ace, and another seals him a very, very important hold. He knows it too, celebrating with a fist pump in the direction of his team.

Big serving at the right time.

Injury or no injury, Djokovic looks to be set for another love hold but he drops a point on serve for the first time in this set while 40-0 up, a backhand winner from Couacaud that even Djokovic himself can appreciate.

But does Couacaud sense an opportunity here? Another backhand winner narrows the deficit but he then overshoots a forehand and the game is Djokovic's.

David Law
Commentator on BBC Radio 5 Sports Extra

There was obviously some panic from Couacaud when he twisted his ankle. I think he's settled down and he's starting to play really nicely.

When Djokovic runs for the ball, he labours to a finish instead of juddering to a stop.

Couacaud knows it too. Lovely serve-and-volley play is followed up with his first ace of the day.

A Djokovic error hands the world number 190 the game to 30 and the Frenchman is very much still in this match.

Again, a serving Djokovic doesn't seem to be bothered by that injury. A second successive love hold as he sends Couacaud flying to all corners of the court.

It's when Djokovic is forced to run and move that he seems to have more of an issue.

David Law
Commentator on BBC Radio 5 Sports Extra

There is something not quite right for Djokovic. You don't hobble around a court when you are in command like that.

Image source, Getty Images

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra

I feel like Djokovic is trying to protect his injury - he is trying to get the footwork going and he's trying not to lunge at anything.

Much better from Coaucaud as he holds a second successive service game, pushing Djokovic into making errors.

A boost of confidence as they change ends?

Any hamstring twinge doesn't seem to be affecting Djokovic too much.

He relentlessly secures a love hold and it's back on to the Couacaud serve.

David Law
Commentator on BBC Radio 5 Sports Extra

Now what has happened to Djokovic? He lurched for a ball and than hopped on his good leg and now he seems to be stretching his hamstring.

It looked as though Couacaud was struggling to contain his opponent after he conceded the opening two points of the set, but errors off the Djokovic backhand bring him back into contention.

From there, another Djokovic error gifts Couacaud game point and he holds as the Serb fails to return a serve.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra

Djokovic is just marching around the court wanting to get on with it.

Sometimes, though, if a match is a little too straight forward you can have fluctuating concentration levels.

Hold up, Djokovic sends down two aces on his way to 40-30 on serve but errors from the Serb mean Couacaud is right in this.

Djokovic has the deal sealed for him on the first advantage though, and that's the first set.

Image source, Getty Images

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra

This is probably one of the biggest moments of Couacaud's career and it might see him through to the end of the first set but I think there will be a lot of discussion and he may not want to continue.

Interesting to see Djokovic using that sort of tactic to make him run to see where he his movement is at.

Image source, Getty Images

Others may want him to stop but Couacaud doesn't. He's facing immense pressure from the world number five on the other side of the net but the Frenchman is giving it everything he's got.

At 40-30, he can't make good use of a game point and then sends a backhand a touch long to hand Djokovic a break point. Djokovic needs only one opportunity this time as Couacaud slams into the net.

The Serb has taken full control here.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra

Couacaud doesn't look particularly happy and his coach has just motioned to him to stop. He did pull up after that long rally.