Carles Puyol and Gerard Piqué are the original odd couple, two men who shouldn't be friends but have turned out to be the perfect partnership – good together and good for each other. Very, very good. So close have they become that Piqué recently took it upon himself to "announce" jokingly that Puyol was getting married and ask if he was going to be the best man; so successful that of the 61 league games they have played together for Barcelona, they have lost only one. And that was more than two years ago.

If Puyol's influence on Piqué is immediately obvious and a little cliched – the serious, experienced old pro guiding the renegade, cocky young star – it is not a one-way street. Piqué has changed Puyol's career too. More than that: Puyol admits that Piqué has changed his life. But for the former Manchester United player, Puyol might be a former Barcelona player. Opposites don't just attract, they enhance – and these two could hardly be more different.

Piqué is the urbanite from a respected family with political, social and economic muscle in Catalonia, son of a prestigious doctor, grandson of a former Barcelona director, handsome, bright, eloquent and outgoing, engaging: the cheeky, self-assured kid who expected to inherit his father's business and says he would like to be Barcelona's president.

Puyol is from the tiny town of Pobla de Segur, in north-western Catalonia, towards the Pyrenees. Population: 3,200. He is serious, reserved, a little uptight, rarely venturing out. Until now.

As footballers they are polar opposites too: Puyol is Barcelona's very own Captain Caveman, playing with his heart on his sleeve and his hair in his eyes, screeching into challenges, never, ever letting up. Rough and rugged. Piqué is "Piquenbauer", elegant and technically gifted, more relaxed, bringing the ball out from the back. Smoothness personified. Each provides what the other does not have. Not only are they good players but they make each other better players too.

When Piqué rejoined Barcelona from Manchester United in 2008, Barcelona had come off the back of a terrible season. Puyol was contemplating a future away from the club. There was pessimism and subsequent signings suggested he might no longer be first choice. Like a little brother that comes back from a voyage of discovery, Piqué showed Puyol that there was life out there, teaching him to lighten up. Bit by bit, he did. It was a new lease of life followed by a new contract.

As for Puyol, he taught Piqué the opposite, on the pitch at least: to get serious. "I know when it's time for a laugh and when it's time for work," Piqué says. "I have shown that I am very focused. I like a laugh, going out and sharing jokes with the dressing room, but I think I have shown I am responsible too." And yet he admits that his partner's influence has been vital, especially during the games themselves.

In the Champions League final at Wembley on Saturday, Barcelona will be up against Manchester United's Wayne Rooney, of whom Piqué says: "I have never seen a player as powerful. The way he goes past people, the intensity, his shot; he is world class." The good news is that, following a chronic knee injury that has limited Puyol to 17 league games, seven in the Champions League and one in the Copa del Rey, he is fit and will surely be included, whether at centre-back or at left-back with Javier Mascherano in the middle. Either way, he is vital. As Piqué will testify, with Puyol it is not so much a question of position as presence.

"I can't imagine a Barcelona team without him," Piqué says. "He wears me out! I remember the day he came back [after the injury]. In the middle of the game I said: 'Puyi, I've missed you so much.' He told me to shut the hell up and concentrate. He never stops. One time, the game was stopped, someone was on the stretcher, and he was shouting at me. I said to him: Calm down, it's 4-0 and there are three minutes left.' He said: 'So what? Focus! I know you.' I was dying with laughter. Puyol keeps you on your toes at all times."

It is not window dressing. If anyone doubts Puyol's importance they need only look at the statistics. The man from Pobla de Segur went on a run of 18 successive victories this season, breaking the previous record held by Ferenc Puskas, and in his 17 league games Barcelona won 16 and drew the other – away at the Santiago Bernabéu. This season, Barcelona have lost only six games in all competitions. Puyol did not play in any of them. No wonder Piqué missed him. "Puyol," he says, "treats every game as if it was the Champions League final."

This time, it actually is. And neither Barcelona nor Puyol's perfect partner can live without him.