When Barcelona and Real Madrid meet, it's always special. Two of the European game's historic giants, Barca and Real have dominated Spanish football for well over half a century.
In Spain, the rivalry has social and political foundations as well, set against the backdrop of the Spanish Civil War, Franco's dictatorship, and their opposing status as symbols of Catalan and Spanish identity.
To the wider international footballing community, the enduring appeal of El Clasico comes down to the footballing pedigree of Barcelona and Real Madrid and, in particular, their continuing association with the world's best footballers.
Most of the all-time greats have, at some point, taken part in this fixture: Di Stefano, Cruyff, Maradona, Ronaldo, Zidane, Figo and Ronaldinho to name just a few. El Clasico's status as the fiercest rivalry in world football is open to debate, but it is without doubt the most glamorous.
And this year it's even bigger.
Thanks to the triumph of Spain's exceptional side in South Africa, there is likely to be at least ten world champions on the field at the Nou Camp this evening. Oh, and Lionel Messi and Cristiano Ronaldo.
These two superstars are the greatest players of their generation: exceptionally gifted; able to change games almost on a whim; similar, and yet different, in so many ways.
Messi is the scampering little wizard, shy and unassuming off the pitch, and yet able to ruthlessly dismantle even the best defences on it. Ronaldo is the prancing matador, blessed with extraordinary technical and physical qualities and an ego to match.
Both have been more than outshining the wealth of world-class names who take the field with them each week; they have been re-defining the boundaries of modern football with the sheer consistency of their excellence.
Messi has 70 goals in his last 71 games; Ronaldo, hampered by injury, has 52 goals from 54 games over the same period. Each motivated by the desire to win global acclaim, these two greats appear to be driving each other on to legendary status.
Tonight's titanic clash will see these two face off at the peak of their powers, and both will have a point to prove. Ronaldo hasn't scored against Barcelona in five attempts, and Messi has never scored or got an assist in seven games against a Jose Mourinho team.
Which brings us on to the other reason why this El Clasico is one of the most anticipated in history: Jose Mourinho.
The 47-year-old has come a long way in the 14 years since joining Barcelona as Bobby Robson's assistant. Winning two European Cups and six league titles in three different countries, 'the Special One' has established himself as the greatest tactical coach in world football.
Mourinho has also been the curse of Barcelona several times, but never more so than in last year's Champions League semi-final with Inter Milan. The 'beautiful defeat' which he masterminded at the Nou Camp was the defining moment of the Italian giants' march to the trophy, and Mourinho will never be forgiven in Catalonia for depriving Barca of the chance to become Kings of Europe at the Bernebeu.
Mourinho's exceptional track record, combined with the fact that he revels in his reputation as Barcelona's bogeyman, made the brash Portuguese the automatic choice to oversee the second Galactico era at Real Madrid.
The fact that Mourinho is now in charge of Real is crucial to the credibility of El Clasico.
Pep Guardiola's Barcelona are the most talented team in the world, and have beaten their Madrid rivals home and away in the last two seasons. Now they face the most talented coach in the world, and he has more than enough weapons at his disposal to end their dominance.
But just how good are Mourinho's Real? They lead La Liga by a point from Barcelona, having scored 33 goals and conceded just three, and have breezed through their Champions League group.
However, their stiffest tests to date have been an aged Milan side and domestic also-rans Atletico Madrid and Espanyol. El Clasico will be the first real indicator of how close Madrid are to becoming a true Mourinho side.
One thing is for sure: this is more than just a game. Last season, Barcelona won La Liga by a point from Real, having won both of their head-to-head encounters. If Ronaldo and co. had but drawn one of those games, they would have been champions.
It's the importance, the uncertainty and, above all, the sheer quality which makes this fixture the event it is.
So just sit back and enjoy the show.