El Clasico, arguably the biggest match in world football will take place on Saturday, and billions of fans from all corners of the globe will be tuning in to see it.
The match between Barcelona and Real Madrid will be played at the the Camp Nou, the home of Barca and a venue which rivals the nearby Sagrada Familia for its transcendent appeal. The match between arguably Europe's two biggest clubs has a long history of magical skill and spectacular goals, bringing joy and jubilation to millions.
But it has also had a far darker side, with tensions rooted in Castille and Catalonia spreading to all corners of the world and spilling over into shocking violence.
One of the most prominent incidents occurred in the very crucible of the rivalry. Fourteen years ago supporters at Camp Nou became so enraged by the sight of Luis Figo, Real Madrid's star winger who had moved from Barcelona two years earlier, that they began to pelt their former hero with missiles - including one of the most gruesome foreign objects which has ever entered a football arena.
Figo had been an icon at Barcelona but the club decided to sell him, heralding a period in which Barca slipped into the doldrums and were eclipsed by the Galacticos of Real. Violence is relatively rare at Spanish football grounds but on this occasion Figo was pelted with bottles, rubbish, and a pig's head which had somehow been smuggled into the stadium. The player emerged unhurt but Catalan enmity towards him has barely abated in the fourteen years since then.
Since the Figo incident, interest in the Barca-Real games has reached a new pitch. Real's Galacticos - Beckham, Zidane, Raul and the rest - brought new international glamour to a fixture which had hitherto been a peripheral event beyond Spain. Then the Barca team of Messi, Xavi and Iniesta made Barca the darlings of world football, a sporting mega-brand on a par with the New York Yankees.
Bosses of the two clubs have been happy to accommodate their burgeoning global audience - tomorrow's fixture has been scheduled for 3.15pm to cater for the Chinese audience. The surge in interest has made the two clubs even richer than ever, allowing them to pay superstar wages and remodel their huge stadiums. But in some of the world's poorest countries it has led to chaos, vandalism and even murder.
Scuffles between fans are common. This video from El Salvador, for example, shows fans bedecked in their club's shirts brawling in the street in 2012 before the fight is brought to a merciful end by the police.
Yet the violence can go much further. In 2011 an Angolan state news agency reported that a teenager hadshot his father to death after an argument about the Real v Barcelona game. His father died at the scene and the teenager then went on the run, according to the report.
In Iraq, the interest in El Clasico has been cited as a source of unity in a country so bitterly and tragically divided over recent years. But in 2013 the match led to fatal discord when a Barcelona supporter reportedly got into an argument with a Real Madrid supporter and beheaded him, according to Baghdad newspaper Al Zaman.
Last year violence spread to South Korea, according to news website Berita Hati, as a man was stabbed at a cafe whilst watching the game with fellow supporters.
In India earlier this year, a man who was celebrating his birthday began to argue with another about whether Messi or Ronaldo was the better player - an argument not strictly related to El Clasico but intrinsically wedded to the rivalry that accompanies it.
A police inspector said the man smashed a glass against a wall, leaving the other man to pick up a shard and cut his friend's throat in a rage. All over an argument which has been played out thousands of times all over the world and most of us would admit was pretty pointless.
But such are the passions this very special game can create. Bill Shankly's old quote about football being more important than life and death is never more apposite than when Los Blancos and La Penya Blaugrana lock horns.
Win, lose or draw, the rivalry is sure to bubble over somewhere in the world tomorrow.