The clock was running down. Time slipped away from Barcelona as they launched yet another attack. Into the penalty area once more. A tiny, pale midfielder hovered, waiting on the edge. The ball was pulled back. No room to control it. No touch to steady himself. An instant shot, beyond the goalkeeper into the net. Goal! Arms in the air, a screaming sprint to the touchline and Andrés Iniesta was buried under a pile of bodies.

No, not Stamford Bridge on 6 May 2009, but Camp Nou a decade earlier – 21 July 1999, the Nike Premier Cup final: the under-15 club world cup. Iniesta was 14. Captain and player of the tournament, he had just scored an extra-time winner against Rosario Central. The man who presented a shy boy with his trophies shook his hand and whispered: "In a few years' time, I'll be watching you do the same from the stands."

He was wrong. When Iniesta repeated the feat in London, Josep "Pep" Guardiola was watching from the bench. "If anyone deserved that goal, it's Andrés," the Barcelona coach insists. "He always moans that he doesn't score enough, as if with everything else he does, he has to get goals too. Tonight he settled his debt for ever."

Guardiola, captain of Barcelona's early-90s Dream Team, was Iniesta's hero. The youngster pinned a poster of him next to his bunk at La Masía – the Catalan farmhouse and Barça residence that stands in the mighty shadow of Camp Nou. Only Catherine Zeta Jones and Michael Laudrup could compete for the space. What Iniesta did not realise was how quickly he was becoming Guardiola's hero, too, how completely he won over his future coach.

It took a little longer to win over others, but now he has. Definitively, absolutely, irrevocably. And not just because of that goal at Stamford Bridge. Now, Iniesta is the apple of everyone's eye, even in Madrid where uniquely he is a Barcelona player you are allowed to love. The campaign builds for him to be short-listed for the Ballon d'Or, a poll has him second only to Leo Messi as La Liga's best and Sir Alex Ferguson admits that, actually, it is Iniesta he most fears. "When I said Iniesta was the world's best, you laughed. Now you can see I'm right," Samuel Eto'o says with a smile.

Guardiola could see it years ago. It is his commitment to Iniesta that has, in part, forced others to see it. "One fundamental change this season is that for the first time Iniesta has been handed full responsibility," argues Felip Vivanco from the newspaper La Vanguardia. Too long confined to cameos, he has taken centre stage.

Barcelona have won many matches without him – Iniesta has endured two spells out injured – but it is not entirely coincidental that since the opening day Barça have lost just three matches and Iniesta missed them all. Small wonder fans are desperate for him to be fit for ­Wednesday. Doubts continue but the prognosis remains positive.

No one feels more need than Guardiola: when he said Iniesta deserved the goal, he meant it. Iniesta had joined Barça aged 12 and people were already talking about Andrésito (little Andres). On the advice of his brother Pere, Guardiola watched him and reported that he had seen a 14-year-old who "reads the game better than me", a tiny lad with touch, pace and vision. Soon, Iniesta's Guardiola poster was replaced by a signed photograph dedicated to "the best player I've ever seen".

On the day Iniesta was called to train with the first-team squad, he could not find the dressing room. Luis Enrique was sent out to find him. Wide-eyed, the 16-year-old thought it was a joke, yet Guardiola was deadly serious when he told team-mates: "Remember this day – the day you first played with Andrés." Pulling Xavi Hernández aside he said: "You're going to retire me. This lad is going to retire us all."

The beauty for Barcelona has been enjoying all three together. One of the secrets of success is continuity, the clarity and commitment with which Barça follow Johan Cruyff's model of pass and move. It is embodied by its midfielders. Guardiola was the prototype, Xavi and Iniesta its custodians. "We are," Iniesta and Xavi agree, "sons of the system."

"Guardiola and Iniesta make Barcelona," says Ferguson. "Rather than their forwards, it's their midfield you have to watch."

And yet Iniesta's game is natural, too. Asked if Iniesta was a born footballer, Guardiola replies: "No, he was already a good player in his mother's womb." Iniesta says: "I play like I always did. At Barcelona you learn loads but it comes out in an improvised way."

Iniesta's style means using his size, or lack of it, as an advantage. "You learn to be sharper, cleverer," he explains. "Small players learn to be intuitive, to anticipate, to protect the ball. A guy who weighs 90 kilos doesn't move like one who weighs 60. In the playground I always played against much bigger kids and I always wanted the ball. Without it, I feel lost."

Everything Barcelona do is through the ball. Their defensive record is the best in Spain not because they have the best defenders, but because they dominate possession, limiting exposure by nurturing the ball.

Iniesta can do the other kind of defending as well: when he played at the base of Barcelona's midfield, his anticipation and awareness won him more possession than any player in La Liga, destroying the "lightweight" cliches. "He is the complete footballer. He can attack and defend, he creates and scores," says Spain coach Vicente del Bosque, while Frank Rijkaard adds: "I played him as a false winger, central midfielder, deep midfielder and just behind the striker and he was always excellent."

That was part of the problem. Jack of all trades and master of them all, Iniesta was one of the few Barcelona players to emerge from last season with his reputation enhanced and became the only Spain player to play every game at Euro 2008. But for so long his versatility played against him.

So too did his timidity. Iniesta was raised in Fuentealbilla, population 1,864, Albacete province, the stereotypical no-man's land on Spain's arid central plain. They say "Albacete, cágate y vete" – have a dump and get out of there – but Iniesta admits he "cried rivers" the day he departed for La Masía. So much did he miss his parents that when they visited not only did he stay with them, he slept in their bed. One Catalan journalist recalls being warned not to ask about his family because he was liable to burst into tears.

Iniesta's father, José Antonio, still carries a photograph of a little kid in dungarees, a ball under his foot. There is no mistaking the identity: Andrés has hardly changed. Some felt he needed to. Startlingly plain, in a dressing room of egos, he shied away. Too often he played out of position or sat on the bench to accommodate others. One occasion was the 2006 Champions League final. If, as he expects, he is declared fit, missing this year is unthinkable.

Some felt Iniesta needed to be more streetwise; others that he required media backing, someone to champion him. "Iniesta is easily Spain's most complete player. He has everything," Xavi says. "Well, nearly everything – he needs media backing." A pigmentation problem leaves him so pale that the running joke on Catalan TV is that he's a glow worm – the children's toy whose face glows in the dark. Quiet, discreet, a man who admits "discos are not my thing," ­others have handed him the ironic title of "Party King".

"I can't imagine I've been left out because I'm 'only' Andrés Iniesta, or because I'm the quiet one," Iniesta said just over a year ago. But many suspected that was exactly what happened and privately he was unhappy. Bit by bit, though, he built a watertight case and, while he could still be moved around, last season he could no longer be ignored – finishing the year with the fifth highest average rating in Spain.

Then Guardiola arrived, the man who even before he took over had eulogised a man on "a different sphere." Iniesta, he said, "is so good, he deserves to play so, so much, and yet he never complains". Backed at last, his lack of an ego now became a virtue. "Everything, but every­thing, he does makes his team-mates better players," says one of Guardiola's closest collaborators.

Guardiola made Iniesta a fundamental pillar and the results have been spectacular: the has the best average rating in the league, the newspaper El País defining him simply as "Nureyev". United have taken note. "I'm not obsessed with Messi, Iniesta is the danger," Ferguson says. "He's fantastic. He makes the team work. The way he finds passes, his movement and ability to create space is incredible. He's so important for Barcelona."

"Andrés doesn't dye his hair, doesn't wear earrings and hasn't got any tattoos. That makes him unattractive to the media, but he's the best," Guardiola said recently. "Sadly, a humble, discreet footballer doesn't sell like one who's loud," adds Lorenzo Serra Ferrer, his first coach. "He's always been good: it surprises me that it's taken so long for people to discover him." Goalkeeper Víctor Valdés agrees, pointedly greeting questions about Iniesta's season with a curt: "Andrés has been the best for years."

Now, he has been well and truly discovered: "When you're this good even your own discretion can't hide your talent," insists one columnist. In fact, Iniesta's mumbling, monotone, unremarkable quietness, once a problem, has ended up making him even more of a star. He has become, as the lead singer of Estopa puts it, "an anti-hero". Being underrated so long has helped him be even more highly rated now; his lack of a selling point has become his selling point; the absence of charm, his charm.

Failing to stand out makes him stand out. The fact that he is so thoroughly decent, so impossible to dislike, is part of his armoury. Phrases like "humble genius", "fantasy without the flashiness", and "the simple star" have become an admiring media's stock in trade.

The pale, quiet, small-town boy has become a hero for his humility, for his football, and of course for that goal. As one overcome columnist put it after Stamford Bridge: "We now know that there is a footballing God. His name is Andrés, he is shy, he is from Albacete and last night he made me cry." Above all, though, he made Pep Guardiola proud.