Tennis, in many ways, is the ultimate test of Darwin’s theory of evolution: the survival of the fittest. On court, it’s just you, your opponent, and the relentless chase for titles and points. A grind that demands everything. Legends like John McEnroe, Chris Evert, and of course the Big Three—Roger Federer, Rafael Nadal, and Novak Djokovic—have proven this again and again. But if you ask Patrick Mouratoglou who embodies that spirit most, his answer might just surprise you.

In an exclusive interview with EssentiallySports’ Andrew Whitelaw, the coach opened up about his journey, his philosophy, and unforgettable moments with some of the game’s greatest stars. Then came the question: who does he believe is the toughest player of them all? Well, that answer didn’t take long.

He said, “I don’t know which way you mean ‘toughest.’ I would say I think the toughest is Novak.” This is coming from a man who coached Serena Williams for a decade and worked with top names such as Naomi Osaka, Holger Rune, Grigor Dimitrov, Simona Halep, and Stefanos Tsitsipas. So why would he pick Nole?

The response was simple yet profound. “Because he had all the crowds against him all his career. He was denied to play tournaments. He refused to do the vaccination. I mean, you need an incredible character, whether you like him or not, whether you agree or not with him. I mean, you have to be really tough to be able to endure that and keep going.”

And it’s true. Novak Djokovic might sit atop tennis’ record books—24 Grand Slam titles, 100 career titles, 428 weeks at No. 1, and countless more milestones. But for some reason, he has so often stood on the wrong side of the crowds. If there’s one thing about Djokovic, though, it’s this: he’s mastered the art of turning pain into power through defiance. For years he has channeled boos, doubts, and disapproval into fuel for victory.

He did exactly that earlier this month at the US Open. In his quarterfinal clash against Taylor Fritz, the crowd got hostile during the third set, booing and heckling as he prepared to serve. At one point, Novak even shouted at the umpire to intervene. In the end? The Serb dug in and took the win in four sets over Fritz. Classic Nole.

And he’s still doing it all at age 38. This season, he’s picked his battles—focusing on the Grand Slams and playing a total of 11 tournaments. Sure, there were some early exits. But at the majors, he reached at least the semifinals in all four. Whether it was falling to stronger opponents like Jannik Sinner or Carlos Alcaraz, or being sidelined by injuries in Melbourne and at Wimbledon, Djokovic kept pushing. Always there. Always in the fight.

So yes, Patrick Mouratoglou believes Novak Djokovic is without a doubt the toughest player in tennis. But he also points to something else — a certain attitude, an edge. Not to mention, his legacy started at a time when many believed no one could beat Roger and Rafa back in the day!

Patrick Mouratoglou hails Novak for his confidence

In an interview with The Guardian, dated September 11, Mouratoglou didn’t flinch when asked if Jannik Sinner and Carlos Alcaraz look untouchable compared to the rest of the men’s field. How would he convince the chasing pack that beating either at a Slam final was possible? The Frenchman grinned. “It’s funny that you’re saying that. When Rafa and Roger were at the top of the game, it was exactly the same situation – the [next] eight players all saying it’s impossible to win a grand slam with those two guys.”

He pointed to a familiar generation that felt that struggle. “When you speak about the generation of French players who were top 10 – Gaël Monfils, Jo-Wilfried Tsonga, Richard Gasquet – they were all saying it. But then a young Novak Djokovic came in and said: ‘I’m going to beat those guys and be No 1.’ And everyone laughed and said: ‘Who’s this cocky guy?’ But he ended up doing it and becoming the greatest of all time.” With Djokovic’s story still unfolding, those words ring more prophetic than just commentary.

Djokovic’s ascent started modestly in 2003 at a Futures event in Oberschleißheim, Germany. Three years later, at 19, he already had two tour titles and a spot in the Top 20 of the PIF ATP Rankings. By 2007, he was breaking through, winning Masters 1000s in Miami and Montreal, reaching his first Slam final at the US Open, and making the semis at Roland Garros and Wimbledon. From 2007 to 2009, his climb was relentless: 14 titles, a first Slam at the 2008 Australian Open, yet four straight seasons stuck at world No. 3, grinding in the shadows of Federer and Nadal.

Now fast forward, and its Sinner and Alcaraz ruling the stage. But Djokovic has already shown he can beat them. Against Alcaraz, he edges the head-to-head 5–4. Sinner, the sharper rival lately, leads 6–4. Slam No. 25 hasn’t landed yet, but Nole has made it clear the story isn’t done. And if Patrick Mouratoglou is right, it’s far too soon to count Novak Djokovic out.