Shortly after being named Massimiliano Allegri's successor at Juventus, Maurizio Sarri boarded a private jet to the Cote d'Azur. The 60-year-old former foreign exchange dealer was off to introduce himself to Cristiano Ronaldo, the five-time Ballon d'Or winner and most expensive signing in the history of Serie A. On the yacht Ronaldo had rented for his post-Nations League holiday, Sarri explained his plans for Juventus and the team's superstar.

He started at the bottom now he's here. From one Cristiano to another. Fifteen years ago, Cristiano Caleri, the captain of fourth division Sangiovannese received a phone call. It was the team's new coach: Maurizio Sarri. Sarri had only recently taken the decision to leave his job at the Banca Toscana and throw himself into full-time management.

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Caleri had already heard the name. Word of Sarri's achievements half an hour down the road in Monte San Savino had spread. "He was already a little bit famous in Tuscany," Caleri recalls fondly. "He'd won a couple of titles [taking non-league Sansovino from Italy's sixth tier to its fourth, lifting the Serie D cup along the way]."

Sangiovannese was Sarri's first gig in professional football. "I still remember the first day," Caleri says. "He called me and said: 'Capitano, I need to talk to you. Come over to my house.' It was the night before our preseason training camp. We went into this room set up for him to analyse games. There were all these VHS tapes." It became clear to Caleri that Sarri had watched a lot of Sangiovannese. He knew the midfielder's game inside and out. "He says this to me. These were his actual words. 'You are my captain. But if you carry on playing like this ... you ain't playing.'"

Caleri bursts out laughing in recollection. "I've always said, in private, he's a comedian," Caleri says. "He's super smart. Seeing him on TV, he can seem a bit dour and hard work, but he's amazing. He doesn't even think he's all that funny. I'm like: 'What do you mean you don't think you're funny. You're a comic.' And you know what Tuscans are like." After all, Roberto Benigni's sense of humour won him an Oscar for "Life is Beautiful."

But back to that night in Sarri's film room. Just imagine if he'd said the same thing to Ronaldo? In the event he did, Caleri is in no doubt that come the end of the conversation, Sarri would have succeeded in capturing the Portuguese's imagination.

"For me, seeing him at Juve, it makes me so proud," he says. "It's bellissimo. He's an extremely intelligent guy and he knows what he's talking about. If he talks football with Ronaldo, he'll spellbind him. He'll arouse his curiosity. Sarri knows what to say. Talking to him, he wins you over."

How exactly? Well, it's quite simply really. Part of it is language. Sarri has a way with words. Getting his message across has never been a problem. "He's a very good communicator," Caleri explains. "You saw how he went to England and how little time it took him to speak very good English. He gets into your head. He beguiles you. He made it easy for us to understand him. The mister was very good at the whiteboard. Very good at illustrating what he wanted."

At the end of the day, though, the answer is to be found in an appeal to the senses; it's the power of an idea, the attraction of an aesthetic. Caleri pauses. "James," he says, "his football was to die for." Even in the fourth tier, "The football we played was good to watch," he adds. "Maybe not as good as his teams play today. Now it's bello, bello, bello. Back then it was about aggression and intensity too. But the football was still good because that's what he wanted. It's what he worked towards. What he studied."

Sarrismo, as defined in the Italian dictionary, "is based on speed and a propensity for attacking football." This was Caleri's experience in 2003. "I played in midfield. I was a bit like the guy he took with him from Napoli to Chelsea ... Jorginho! Just not quite as good," Caleri says with self-deprecation.

"I'd take the ball off the centre-backs, play a pass, watch it, 'Niiiice' I'd think to myself ... But he said to me: 'No, Cristiano. You're the guy who has to set the tone for this team. You need to play with intensity. Be aggressive. Take the team by the scruff of the neck.' He made me understand that I had to give it my all, I had to be his condottiero. He transformed me. I owe him a lot. He taught me that football is intensity, aggression, desire, determination."

Sarri's association with the pursuit of beauty through football often has meant that the emphasis he puts on mentality and toughness gets overlooked. He is categorised as a purist, not a winner. Yet when Caleri worked under him, Sarri was delivering promotion after promotion -- three in four years to be exact -- taking teams to places they'd never been before. Success mattered to him and Sarri drove it into his players.

Caleri tells a story about training in winter. Sometimes the pitch would be frozen, but sessions were never abandoned. "He threw himself into it. He wanted us to never give up and train regardless of what the conditions were like. There were times when we turned to him and said: 'No, mister, it's dangerous'. But he'd find a way of getting us to train all the same. He'd never give up. He'd say: 'Come on, we can't let anything get in our way. We need to give it our all. He was so determined and managed to pass that determination and desire onto us."

For Sarri, Sangiovannese must stop at nothing to achieve the aim of promotion to Italy's third division. As such Caleri made his coach a wager. Famously superstitious to the extreme, Sarri was in his black tracksuit phase. "You know that colours never existed to him," Caleri says. "He only ever wore black [for good luck]. So I made him this bet. If we won the Serie C2 title and got into C1 with this little team from San Giovanni di Valdarno, a town with a population of 10,000, it would have caused a sensation. Everyone would go crazy. So I said if we win the league, you have to come to our final game of the season in one of my pink shirts. We won the league and he turned up in pink. He's an exceptional guy."

Watching Sarri's rise has brought Caleri tremendous satisfaction. "The beautiful thing is when he got to Serie B with Empoli and then Serie A, all the corner routines and other schemes he used to make us practice, he still did them! The same ones! The thing is it's different watching them on Sky than on local TV. They become even more beautiful. People would see them on Sky and go: 'Madonna, did you see that?' And he'd been doing these things for years just with players who weren't as good, guys who played with me in C. The higher he went, the more he found himself working with guys who could strike the ball better and put it close to or on the penalty spot, the exact place he wanted it. And his schemes started coming off even better."

Now that Caleri's playing days are over, he holds down two jobs. One in insurance, the other in football. He took his coaching badges five years ago, but you won't find him in a dugout like Sarri. He is the current sporting director of Sangiovannese, and when there's a chance to go and see his old coach, Caleri takes it. In fact, he was planning on driving up to Turin to watch Juventus train, only for Sarri to come down with pneumonia.

Continassa, the Italian champions' state of the art training ground, feels a long way from San Giovanni di Valdarno, but behind its walls reside elements of Sangiovannese. It's a source of immense pride to Caleri, and it goes beyond Sarri too. Loris Beoni used to coach Sangiovannese's youth team. Gianni Picchioni hails from San Giovanni di Valdarno. The pair of them now assist Sarri at Juventus. They train Ballon d'Or and World Cup winners on a daily basis. How about that?

"I definitely thought he'd do well," Caleri says of Sarri. "But picturing him coming this far ... all the way to Juve ... that's not easy. I expected him to do well. He was just so good at his job. A really cultured guy. Seeing him at Juve, well, it makes me emotional. I'm so happy for him. So happy. He deserves it."