For Alcaraz, Ferrero is very strict, but that's a good thing: "If he wasn't so demanding, I'd probably have gone off the rails".

Carlos Alcaraz is a real phenomenon.

At just 21, the Spaniard has already carried off 4 Grand Slam titles, including Wimbledon less than a week ago.

So, inevitably, the more he wins, the more eyes are on him.

Asked about the recipe for his success, the El Palmar prodigy praised his coach, Juan Carlos Ferrero, at some length: "He's a tough nut to crack. He's a very serious person when it comes down to it. In terms of work and discipline, he's very tough, but he's also very, very funny when he needs to be.

He's very good at differentiating moments, but, yes, he's very strict about everything, on the court, about professionalism, about the things I need to improve on off the court, like the phone, punctuality, rest, etc.

But I think that's why I'm where I am today, that's why I've grown so fast, because if he wasn't so demanding, I'd probably have gone off the rails."