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!

Image source, EPA

So far so good for Novak Djokovic, who has not had to expend too much energy so far, conceding just two points on his serve, while breaking Joao Fonseca twice.

Rafael Jodar amps up the crowd after earning a second break point of the set with a forehand winner, encouraging them to turn up the noise.

However, Alex Michelsen comes up with a big serve out wide to take the game back to deuce and follows it with an ace. A wide backhand from Jodar completes the hold for the American.

Jodar holds to 30.

Novak Djokovic is in the driving seat early in this match but he doesn't seem altogether happy with things, grumbling away at his coaching team.

He's at the end of the court that looks into the sun so there's a bit of glaring up at the sky, and fiddling with his pristine white cap.

But whatever his mood, his game looks sharp.

The 39-year-old earns two break points - and when Joao Fonseca nets a backhand, Djokovic has a double-break.

Novak Djokovic wins a 19-shot rally and there is a real sense of him trying to impose himself on this match befoe Joao Fonseca can find his way into it.

A beautifully timed lob secures the game.

Annabel Croft
Former British number one on BBC Radio 5 Live

That was a lung buster that point and it took a lot to get to the point didn't it. You can see Fonseca is looking pretty relaxed, he doesn't look too intimidated yet.

Rafael Jodar had an opportunity for an early break, leading 30-40 in Alex Michelsen's opening service game, but the American came through with a forehand winner on the approach before winning deuce.

Jodar holds to 15 with an ace down the T.

It's on serve in the fourth set.

It's perhaps not surprising Joao Fonseca seems a bit overawed at the moment. After all, Novak Djokovic made his French Open debut a year before the Brazilian was born.

However, the 19-year-old will feel better after holding his serve, especially blasting down an ace to clinch the game.

Annabel Croft
Former British number one on BBC Radio 5 Live

It is a fast start from Djokovic, exactly how he wanted to come out of the blocks and stamp his authority.

Image source, Reuters

Novak Djokovic has the air of a player who doesn't want to spend three and a half hours on court, as he did in seeing off Valentin Royer two days ago.

The 39-year-old holds serve to love.

Joao Fonseca won the toss and elected to serve but he seems a bit nervous, and Novak Djokovic pounces immediately to earn two break points.

And the 24-time Grand Slam champion has the early break when he chases down a Fonseca drop shot to force an error.

Image source, Getty Images

Teenager Joao Fonseca, one of the rising stars of tennis, is relishing the prospect of his first meeting with 24-time Grand Slam champion Novak Djokovic.

"I'm going to enjoy every moment playing against an idol, the GOAT of the sport," said the 19-year-old after his second-round win over Croatia's Dino Prizmic.

The Brazilian is 20 years younger than Djokovic but like the Serb, his path to the third round has not been straightforward.

He had to come from two sets down to beat Prizmic, yet his match was still shorter than Djokovic's four-set struggle to overcome Valentin Royer.

Fonseca is still learning his trade but if he can get his fizzing forehand firing, he could cause the former world number one real problems.