We've just hit the four-hour mark and all of a sudden, Alex Michelsen springs into life and arrows a backhand winner across court for two break points.

He might not be playing to his full potential with some reported back problems, but the American bites down and secures the break.

Whose match is it from here?

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Joao Fonseca showed a few signs of frustration after being broken in that game, with his coaching team trying to encourage him.

Meanwhile, Novak Djokovic looks determined to put his foot on the accelerator now. A glorious backhand down the line is the pick of the points as he holds to love.

Annabel Croft
Former British number one on BBC Radio 5 Live

That was breathtaking. What a point from Djokovic. It seems a while since she has played a point like that, the finish from that forehand was just stunning.

A beautifully worked point from Novak Djokovic earns him two break points.

He needs just one, cracking a cross-court forehand to secure the first break of the second set.

Rafael Jodar's backhand down the line is a weapon and he brings it out at just the right time to put the pressure on Alex Michelsen.

The Spaniard secures break point but misses a golden opportunity as he goes into the net.

Alex Michelsen steps up to hold during deuce and keep himself in the match.

Annabel Croft
Former British number one on BBC Radio 5 Live

I think Djokovic enjoyed that, he is saying give me some more! That was a special point. This tennis is really ramping up.

The crowd are a bit subdued at the moment - it's the hottest part of the day - but a brilliant 21-shot rally brings them to life.

The long exchange of shots ends with a bit of ping-pong volleying at the net before Novak Djokovic wins the point and then raises his arm aloft.

The Serb goes on to hold.

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Novak Djokovic is having an intense running conversation with former top 15 player Viktor Troicki, who is part of his coaching team.

Whatever they're talking about, it doesn't help him in this game, which Joao Fonseca wins to edge ahead in the second set.

Another routine hold for Novak Djokovic.

Joao Fonseca needs to somehow upset the Serb's rhythm but that's easier said than done.

The perfect start to the deciding fifth set for Rafael Jodar.

At break point his shot clips the line and after a check from the umpire, he raises his finger to signal the Spaniard has won the point.

He follows it up with a brisk hold to love and the pressure is all on Alex Michelsen at the moment.

Joao Fonseca lost his opening service game in the first set but looks much more at ease on Court Philippe-Chatrier now.

The 19-year-old, who is aiming to become the first teenager to beat Novak Djokovic at a Grand Slam, holds to take first blood in set two.

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Spanish 27th seed Rafael Jodar takes the match to a fifth set as he secures the hold against Alex Michelsen.

American Michelsen will be hoping the problem which forced him to call for a medical timeout at the end of that fourth set will not hamper his game in the closing stages.

Image source, Getty Images

Like the great champion he is, Novak Djokovic keeps his composure and serves out the first set, clinching it with a lovely drop shot that has Joao Fonseca flailing.

So far, it has gone to plan for the 39-year-old, but he will need to keep his level high to hold the improving 19-year-old at bay.

Image source, EPA

Joao Fonseca is really in this match now.

The Brazilian holds to 15 and pumps his fist at his coaching box as he goes to his chair.

Even if he can't stop Djokovic from taking the first set, Fonseca has shown the world number one that he has upped his game and isn't going to be rolled over.

Rafael Jodar is one game away from taking this match to a fifth set after coming through a testing hold against Alex Michelsen.

American Michelsen vents his frustration by bashing his racquet on his head.

There's a medical timeout as the physio sees to Michelsen, but it isn't for his head. The American appears to have some back pain.

Annabel Croft
Former British number one on BBC Radio 5 Live

I could sense that break from Fonseca was coming and the crowd are behind him as well.

Hang on a minute - just when Novak Djokovic looked to have the first set in the bag, Joao Fonseca beaks.

The teenager shakes his fist after earning the first point and then Novak Djokovic prods a backhand long.

the 39-year-old then nets a flashy jumping backhand to go break point down - and it's Fonseca who comes out on top.

Image source, EPA

Joao Fonseca double-faults to go 0-30 down and then Novak Djokovic unleashes a return winner to earn three set points.

But the 19-year-old Brazilian shows real guts to save all three and goes on to hold.

In the midst of a lengthy game, Rafael Jodar gets the help of the tape as a shot which was drifting wide clips the top and drops inside the court.

The 19-year-old Spaniard makes the opportunity count as he goes on to secure the break with a passing forehand.

He amps up the crowd by raising his arms in the air in celebration.

Annabel Croft
Former British number one on BBC Radio 5 Live

I don't think Djokovic can look any better than he does now. He is making Fonseca run a lot!