Novak Djokovic, Alexander Zverev, Italian Open, Andre Agassi, French Open
Andre Agassi, a heaven-sent gift for the struggling Novak DjokovicReuters

When Novak Djokovic announced that he was splitting up with his entire coaching staff, by deciding to go for "shock therapy", you knew a big-name coach was going to arrive, someone from the top bracket.

So, it came as absolutely no surprise when Djokovic, after losing to Alexander Zverev in the Italian Open final, announced Andre Agassi was going to coach him for the French Open.

Ah, how Djokovic, who turned 30 today, would love to rewind a year and relive that brilliant French Open victory in 2016, a title got him the career Grand Slam, but also a title that has triggered a bit of a downward spiral.

Since winning the championship at Roland Garros, Djokovic has failed to threaten in any of the Grand Slams.

Djokovic was knocked out by the big-serving Sam Querrey at Wimbledon in the third round.

Then, the quest to win an Olympic gold medal ended in the very first round, when Juan Martin Del Potro sent the Serbian out in Rio.

It looked like the old Djokovic might be back when he reached the US Open final, only for the 12-time Grand Slam champion to go down to Stan Wawrinka. After losing that final, Djokovic admitted nerves had gotten the better of him in important moments, something that should have raised a lot more eyebrows than it did, because it is Djokovic's ridiculous mental strength, in those big points, that had pushed him up to the top of men's tennis.

In the season-ending ATP World Tour Finals, Djokovic suffered another finals defeat, this time to Andy Murray who cruised home in straight sets to ensure he would end the year as the world number one.

A new beginning was expected, with Djokovic, fresh from a break and raring to go, looking to smash everyone down and defend the Australian Open, the first Grand Slam of 2017, and a major he has made his own.

However, again, that Djokovic mental and physical strength were non-existent as he suffered a five-set defeat to Denis Istomin, ranked 117 at the time, in the second round in Melbourne, with that major eventually turning out to be one dominated by the golden oldies.

Novak Djokovic, French Open, trophy, Andre Agassi, coach
Novak Djokovic with the French Open trophy that he won last yearReuters

So, here we are then, back at Djokovic's last point of utter domination, when he went on to win his first French Open title.

Yes, Djokovic was helped by the fact that Rafael Nadal had to withdraw with a wrist injury, but like great champions, he took advantage, saw off the challenge from Murray and lifted the trophy he had been gunning for, for a long, long time.

This year, though, won't be easy.

Djokovic will have to face a resurgent Nadal, looking like he is back to his best and formidable as ever on the red clay.

Murray might not be playing the greatest of tennis at the moment, but you know he will step up a gear in the big tournaments.

Then there are the likes of Dominic Thiem, who ended Nadal's brilliant clay form at the Italian Open, and Zverev, who now knows what it takes to beat Djokovic in a big final.

Roger Federer might have decided against playing at Roland Garros this year, but if Djokovic is to defend his title, he is going to need to find that mental strength that made him nearly unbeatable.

Andre Agassi, Novak Djokovic, US Open trophy 2013, French Open, coach
Andre Agassi could provide Novak Djokovic the inspiration he needs to defend his French Open titleReuters

Maybe, Agassi is the one to get the Serbian back in the right frame of mind. While talking about Agassi's appointment, Djokovic seemed to suggest he called on the American not just to help him on the court, but outside as well.

"Andre is someone that I have tremendous respect for as a person and as a player," Djokovic said. "He has been through everything that I'm going through. He understands the game amazingly well. I am enjoying every conversation that I have with him.

"Also, he's someone that nurtures family values, philanthropic work. He's a very humble man, very educated. He's a person that can contribute to my life on and off the court a lot. I'm very excited to see what is ahead of us."

Agassi won't stay the entire course of the French Open, with Djokovic saying the eight-time Grand Slam winner will only be available during "certain times" in Paris, with a decision for a longer commitment taken depending on how that goes.

Djokovic showed signs of good form at the Italian Open last week, reaching the final, before suffering a straight-set defeat to the excellent Zverev.

Clearly, the former world number one is still not quite where he needs to be, but, who knows, Agassi could be the man to take the Serbian back to those ridiculous heights that made him near untouchable in the men's game.

Zverev wins Italian Open by beating Djokovic