Dani Alves sits behind a large desk in his office in Sant Just Desvern, a small town near Barcelona, wearing a shirt, tie and jacket. Behind him, a cabinet containing countless football shirts, folded neatly, photographs and trophies. Lots of trophies. Through the glass to his right, a board meeting. Through the glass to his left, reception: a leather sofa, the morning's papers, a television showcasing danialves.com and replaying highlights from the 2011 European Cup final — "the best moment of my career," he says. The only thing missing is a box of business cards. But what would they say? "Daniel Alves da Silva, right-back"?

It would be the most inadequate business card ever, after "Leonardo Da Vinci, painter and decorator". "But," protests Alves, "I am a right-back." A right-back, full-stop? "No, not full stop, no." It's just that Alves's concept of full-back, his philosophy of football, is different. So is his coach Pep Guardiola's. "In the Brazilian school, the emphasis is on attacking," Alves says, "but that doesn't mean I'm not a full-back."

"Take Gareth Bale, a player I love," he explains. "He's a full-back in the Brazilian mould, he has a similar idea. In Europe [Spurs] play him as a winger, but in my team he'd always be a full-back. People get scared and play attacking full-backs as wingers. They think they will attack more, but often they attack less and less well. It happened with Roberto Carlos: as a winger, he was less effective, he needs to start his run sooner. Bale is more skilful and good as a winger, but at Barcelona he would be a full-back."

It is not about names; it is about concepts. This is not a pitch for Bale, although Barcelona have watched him. It is an illustration. When the Chelsea manager, Roberto Di Matteo, scrawls on the tactics board ahead of Wednesday night's Champions League first leg, he'll have a dilemma when it comes to Alves — the player, says Guardiola, who allows Barcelona to play four or three at the back in the same game.

The driving force behind the most successful Sevilla side in history, topping the La Liga assist charts one season, involved in more moves than anyone else in Spain the next, Alves found the perfect home at Barcelona when he arrived in 2008. They, in turn, found the perfect player: right-back, right-midfielder, right-winger, centre-forward, central midfielder, support striker, tackler and playmaker, all wrapped into one, hyperactive ball. Athlete and aesthete, ultra-talented and ultra-competitive, a footballing Sonic the Hedgehog, in your face and in your penalty area. And his own. As Jorge Valdano put it: "When Dani Alves runs up the pitch, he meets himself running back down it."

The previous season Chelsea had baulked at the €36m (£29.6) price for just a defender. But Alves has never been just a defender. He was one of only two signings Barcelona made — the other was Gerard Piqué — after two years without winning anything. Then they won the treble. A glance at the trophy cabinet tells the story: three league titles, two Copa del Reys, four Spanish Super Cups, two Uefa Cups, three European Super Cups, two Champions Leagues, two World Club Cups. Eighteen trophies since 2006: no player in the world has been more successful at club level over the last six years.

When Lionel Messi broke Barcelona's goalscoring record, Alves had provided 31 of them — more than anyone else. In 2009-10 he gave more assists than anyone else in Spain; this season only Messi, Ronaldo and Angel Di María have provided more. According to statistics from Opta, only Messi and Xavi have had more touches on the ball in the opposition's half than him and only two players have completed more passes in the final third. 63.5% of his touches are in the opposition's half. Ah, say the critics, but that is because he does not defend.

Alves's response is sharp: "People automatically think that because you attack, you can't defend. Not true." Again, the question of concepts and of adaptability. Besides, he says, he can defend. "What we cannot do is play with 11 men behind the ball. Defend? Defend what? You can't 'defend', in the traditional sense, a team that does not attack you. And we defend by stopping them attacking us. Against Madrid I hardly attacked because they counter so well. We needed control; if not, they steamroller you. If I am asked to defend, it's tough because I like attacking, I like to participate, but I will do it.

"We're taking football back to its origins. Interests have changed everything: all that matters is winning any way you can. If you don't, you are worthless. For me, that's not football. When I was young I wanted to win but I played because it was fun. Our approach has a bit of that. Enjoyment. I love football, adore it. We have to give something back to the fans.

"Because I already had a similar concept to Barcelona, that made coming here easier. It was also why Barcelona signed me: they knew I would fit in. Their game is touch, technique, combination, attacking. Barça always sign players that share the approach, with the right characteristics," Alves says, adopting a mock sporting director's voice. "Barça never say 'People are talking about him, let's sign him'. No. Look at Alexis [Sánchez]: he's spectacular, but he was not so mediático. Yet Barca paid a lot of money because they knew what he could bring.

"The most difficult thing about Barcelona is not the way they play but the way of understanding the game. Tactically, I've improved under Pep, learning to do the simplest thing, which sometimes is the most difficult thing. But the key is the way we pressure — and the first person to lead the pressure is our best player, Leo Messi. That's the starting point for an entire philosophy. I never thought that a team could pressure like we do: from minute one to minute 95, pressuring the ball and in the opposition's half. Pep's greatest success is convincing players, even great players, to do that."

He recalls Guardiola's message before the 2011 final, a dominant 3-1 victory over Manchester United at Wembley. "The only thing he asked us to do is attack – it's the only way to win, especially against physically strong teams with devastating counterattacks. You can't let them have the ball: if they have the ball you have to get it back. Quickly. After the final, [Nemanja] Vidic congratulated us, saying we had a spectacular team. When you hear that from people who really know about the game and how difficult it is to be a footballer, it's the leche, the business. People attack you sometimes and you think 'you don't know anything'. When I'm sitting on the sofa I'm the best player in the world but you have got to go out there and play. Vidic's words meant a lot."

For Barcelona, more so. They have encountered resistance and accusations. Alves, 28, speaks intelligently and analytically; he knows his image is different and admits that sometimes he does not recognise himself on the pitch. Asked if he would ever be a referee, he sounds terrified: "No!" he exclaims. "People already don't like me; imagine what it would be like if I was a referee!" It is clear that the pressure counts. "It can be irritating that people look for the flaws or question the validity of your success but that's an expression of their impotence, really; a way of detracting attention," he says. "Instead of concentrating on competing, some focus on dragging you down.

"People think that footballers just have a kick around with their mates. If they win, fine; if they don't, that's then fine too. No pasa nada. No. You have an obligation and responsibility. I've been in the game for so long that I can handle it but there are still moments when the nerves get the better of you. The fear of losing makes you better because it stops you cruising. Big teams and big players are scared sometimes too. What you can never be scared of is playing."

Talk of being "scared" leads to the 2009 semi-final that casts such a shadow over this clash. Why did Chelsea lose? Alves's answer is direct: "fear." "There's no doubt that was the hardest game we've played," he says. "People say Chelsea would have won but for the referee, but what can we do about that? I think that [in 2009], Chelsea didn't reach the final because of fear. The team that has got a man more, at home, winning 1-0, should have attacked us. Chelsea lacked the courage to take a step forward. Instead, they took a step back and they paid for it. When we saw they were not attacking us, we realised they had renounced the game. They were satisfied with 1-0, they were satisfied but forgot that at 1-1 we were through. All they did was get rid of the ball. They gifted us possession — and the worst thing you can do with Barcelona is give them possession."

Alves's discourse has come full circle. "Of course," he adds. "If you don't have that concept of football, that's what happens. Te quedas atrás, te quedás atrás, y te quedas fuera. [The rough translation runs: You go back, you go back, you go out.] You can never stay back. You can't! You have to go forward. Stay back: losers. Go forward: winners." Now, that is something Dani Alves could put on that business card.