Editor's note: The following is an exclusive extract from Graham Hunter's new book, Barca: The Making of the Greatest Team in the World.

Rosario, Argentina, 2000. Leo Messi is 12 years old and, although coveted by both Newell's Old Boys and River Plate, neither club can afford the approximate $1000 per month across two years for the growth hormone treatment that will correct a deficiency and allow him to reach his natural height at a normal rate of growth. His father, Jorge Messi, had persuaded his employers and another local business to sponsor the initial cost of treatment, but that, too, has become unsustainable.

The story of the boy who would become the world's greatest soccer player needed an another hero.

So it was that two Argentinian intermediaries in Buenos Aires heard about this amazing kid who couldn't grow properly. They phoned a contact, Horacio Gaggioli, in Barcelona, who brought into this drama a central character -- Josep Maria Minguella, a ubiquitous figure in the modern history of FC Barcelona and an extraordinary man.

Minguella was taken on at FC Barcelona as a translator to the English coach Vic Buckingham back in 1970. He became a coach, the manager's assistant, a youth-team organiser, a scout and a player agent. He's also the man who brought Diego Maradona, Romario, Hristo Stoichkov and, finally, Leo Messi to the Camp Nou.

Minguella recalls the process of being convinced by Messi's talent, and then trying to convince others. "I first saw him when he was 12 and he was not big," he told me. "Physically, there were doubts whether he'd ever become a good footballer in Europe, but as soon as I saw the videos it was like seeing the light. I believe Leo comes from a marvelous planet, the one where exceptional people like violinists, architects, and doctors are created. The chosen people.

"He was instantly similar to Maradona. Left foot, No.10, same mentality. All kids like him wanted to be playmakers, to emulate Maradona, but I knew there were both serious possibilities and serious problems.

"Barça were not too interested. They said, 'It will be 10 or 12 years before we see the benefit'. I was determined, so I paid his ticket across to Spain, him and his father, and installed them in the Plaza Hotel in Plaza Espanya.

"In the training sessions the coaches could see what he had, but there were weeks of discussions, because some directors thought he was too small, some liked him, but no-one would take decisions. I called Charly Rexach, who had been my friend for years, and was a football advisor to the Barça president, Joan Gaspart. Charly prepared a friendly match."

It was played on the outside pitches at the Mini Estadi (the smaller stadium next to the Camp Nou, where Barça B play), hard, flat artificial turf, and Messi, despite being under-developed for his age, played with kids of age categories above his -- and he shone.

"Charly saw immediately what others had been scared to commit to," said Minguella. "But things had dragged on for so, so long by that stage that Leo's dad was frustrated and losing faith. So we went up to Pompeii tennis club in Montjuic, where I was the president. I was confident in Rexach, but the Messi family had been here one month or more and they thought it was all going wrong.

"Therefore, famously, Charly took a paper napkin, laid it on the table and wrote: 'In Barcelona on the 14th of December 2000 and in the presence of Mr Minguella, Horacio Gaggioli (representing the Messi family), I, Charly Rexach, technical secretary of FC Barcelona, use my position, despite there being some whose opinion is against it, to commit to signing the player Lionel Messi so long as everyone sticks to the financial terms we agree on.'"

However, time was running out. Jorge Messi was tired of being messed about.

He had ended up in a similarly frustrating mess with River Plate a few months previously and now, on the other side of the world and separated from the rest of the family, Barça appeared to be making fools of themselves and the Messis.

By this stage -- although Minguella swears he would never have contacted Real Madrid -- Barça's great rivals were aware of this phenomenal prospect, and of the slow progress being made with the Catalan club. Messi didn't have a professional contract in Argentina and a coup would have been straightforward.

Taking on faith that the weird 'napkin-contract' was valid, father and son re-committed to Barça, Jorge was promised a paid role (at around ?42,000 per year) within the club's youth development and scouting system and his son's career at the Camp Nou began. Well, almost.

It still took until March 2001 for a full junior (rather than professional) contract to be signed, during which another of the heroes in this story, Joan Lacueva, Barça director general at that time, also tired of the club's flat-footedness and began paying for Messi's growth hormone treatment out of his own pocket.

"I was the director general, in charge of administrating youth football at Barça. I was aware there was a player taking trials at Barça, a certain Leo Messi. Josep Maria Minguella came to me and said, 'I've got this kid who's going to play for the first team one day. I like him a lot and we need to find out why his dad isn't happy and why things aren't progressing as they should be. I want to get this sorted out'.

"I went to the head of the sporting side of the fútbol base [Barcelona's academy system] and said, 'There's a player we're trialling and I need to know everything about him so that I can decide whether to push this through or not'.

"The more I spoke to all the coaches the more I heard the same incredible reports, so I insisted that we needed to sign this guy.

"Whilst all this was happening, a meeting had taken place, at the father's insistence, with Carles Rexach, the technical director. They met at the tennis club and signed on that famous napkin. It was obviously not a legal document, so Messi's father came to see me that afternoon.

"I couldn't produce an official document immediately because the board had to agree it first, so I decided to copy the agreement on the napkin onto official club stationary, which I then signed. From there it went to the board, where it had a mixed response. Some directors were supportive, but others considered that, at 13 years of age, the lad was far too small and was more suited to indoor, five-a-side, or even table football.

"The proposal was that we pay this kid more than we had ever paid a player at his stage, but by the end of the meeting they had agreed to start the process of signing Messi to the club.

"I spoke to Josep Borrell in Barcelona's medical team and told him about the treatment the player required. His advice was to start as soon as possible. That meant someone had to pay for the treatment and, as far as I remember, I paid 152,000 pesetas for the first round of injections. I wasn't motivated solely by the kindness of my heart, though. Given that Messi wasn't yet a Barça player, I couldn't justify paying for it out of the club's funds and later, when he was playing for the club, I was reimbursed."

Lacueva is one of those, like Rexach, Minguella and only one or two others, who can sit back in a privileged seat at the Camp Nou, or at home on the sofa, and watch Lionel Messi write footballing history with a sense of immense satisfaction in having participated in signing him in the face of opposition and with intelligence, honour and alacrity.

Barca: The Making of the Greatest Team in the World, by Graham Hunter is available now as an ebook at all major retailers and direct from the publisher, backpagepress.co.uk. The book is published on February 17. Follow @backpagepress on Twitter.

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