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However, the question that any football-loving Martian might rightly ask is why should two clubs that are 630 kilometres apart, according to my road atlas of Europe, be such deadly enemies?

Many of the other great match-ups in Europe - think about Inter v Milan, Lazio v Roma or even Fenerbahce v Galatasaray - take place between teams in the same city, but the sheer animosity and tension surrounding this Spanish derby transcends distance.

"Two languages, two peoples... two countries?" wrote Andy Mitten, the author of .

Within one frontier, he perhaps should have added.

It's as much of a clash of ideologies and history rather than a kickabout between the 22 men, two-thirds of whom are not even Spanish, who will face each other on the football field.

"Derbies overseas often have a more overt political and religious context," added Mitten, and he couldn't be more accurate about the emotions that stir behind Spain's big match.

The motto of Barcelona is 'More than a club' and the reigning Spanish and European champions have aimed for most of their 110-year history to be exactly that, even if they were founded by a Swiss immigrant, .

Keeping it simple, as there are plenty of books on the subject, Barca broadly represents the autonomous regional aspirations of against central control from which in their opinion, and many others of all political persuasions, is embodied by Real Madrid.

Football fans from Castile and Catalonia have only been at each other's throats since 13 May, 1902 - the date of the first match between the two clubs, which Barca won 3-1 at what was then just plain Madrid FC - but the legacy of disharmony between the two regions goes back centuries.

And it wasn't long before Madrid-Barcelona matches became more than a game.

Firstly, Madrid got the Real - royal - prefix in 1920 and they then became the favoured club of Europe's longest-lasting 20th century dictator , who came to power in 1936.

For much of Franco's 39-year dictatorship the was the only place in Spain where Catalan could be openly spoken and the police wouldn't intervene.

"The Catalans feel Catalan first and Spanish second, and to prove it they have fought wars and made revolts against Madrid. Until recently, they always lost. This century, for instance, in the civil war of the 1930s Catalonia held out longest against General Franco, but then suffered under his yoke until he died in 1975," commented Simon Kuper in his award-winning Football Against The Enemy.

´óÏó´«Ã½ presenter Gary Lineker, who is still a derby-day hero at the Camp Nou after scoring a hat-trick in Barca's 3-2 win over Real in 1987, added: "You can't make a comparison with the Everton-Liverpool derbies or the north London matches I played in for Spurs against Arsenal where you have two teams from the same city and a split crowd... you were playing in front of 120,000 people and there were no away fans."

Having been at many of the derbies in the Camp Nou since 1997 - including the infamous match in 2001 when a pig's head was thrown at the 'traitor' - I can testify that there is nothing at any other ground in the world that I've been to which can equal the cauldron of noise from the 98,000 Barca fans (the current capacity of the Camp Nou) baying for the blood of the Real Madrid players when they walk out on to the pitch.

Not even the reverse fixture in the generates such an intimidating atmosphere.

"The windows of our coach would routinely be smashed by bricks on every trip to Barcelona. That was truly frightening. On the short trip from the hotel to the Nou Camp we'd all cower down on the floor as the driver put his foot down," recalled former Real player Steve McManaman.

Despite the fact that some of the ancient political grievances have ebbed away with the advent of democracy, enhanced by further self-governing rights being granted to Catalonia three years ago, the match continues to be a focal point for both clubs' fans.

Barca's 6-2 thrashing of Real Madrid in the Santiago Bernabeu indirectly led to the events of last summer which we all know about.

Samuel Eto'o (centre) and Sergio Busquets (right) celebrate Barcelona's 6-2 win at the Bernabeu in May

The day after that match in May, after sitting quietly on the fence for a few months, Florentino Perez let his friends in certain Spanish media know that imminently he would be announcing the fact that he was looking to return as Real president.

Once he returned unopposed, Perez then embarked on his €270 million spending spree which saw Real sign Cristiano Ronaldo, Kaka and another four top-class internationals.

It's debatable whether he parted with the almost-obscene amount of money in order to win a historic 10th European crown or just to avoid another humiliating defeat at the feet of Real's eternal rivals.