Mucho mono or Mucho morro?

Barcelona and Real Madrid play at the Camp Nou tonight in the quarter final of the Copa del Rey. The Catalan team leads 2-1 from the first leg. It will be the first clásico match in Barcelona since the two teams met in the dramatic second leg of Spain's Super Cup, a game that Barça won 3-2 and 5-4 on aggregate. In the third minute of extra time, Real Madrid's Marcelo, a black Brazilian player who sports a shaggy Afro, hacked down Barcelona debutant Cesc Fàbregas on the touchline by the two dugouts. The ref immediately drew a red card. Monkey chants echoed around the 100-seater Camp Nou stadium.

Over the next few days, the Spanish press focused on the mêlée that followed Marcelo's ugly tackle, and in particular José Mourinho's intervention. The Real Madrid manager poked the eye of Tito Vilanova, Barcelona's assistant manager. The racist abuse got little or no mention, just as the furor in November over Sepp Blatter's controversial comments about racism - that players should shake hands after an incident and continue playing - failed to get a mention in Spain's main soccer newspapers, AS and Marca.

The previous May, during the second leg of the Champions League semi-final at the Camp Nou, Marcelo endured a torrid night. Any time he did something conspicuous, fans dotted around the stadium started shouting "mono"; others grunted, "Ugh, ugh."

At the time, Marcelo was in the crosshairs of Barcelona's fans. On the eve of the match, Real Madrid posted a video on its website of Barcelona midfielder Sergio Busquets' alleged racist taunting of Marcelo during the first leg, which included subtitles. The footage showed Busquets cupping his mouth with his hand to avoid detection. Barcelona insisted Busquets hadn't called Marcelo a monkey. He wasn't mouthing the words, "mono, mono," the club explained. He was just saying, "mucho morro".

Although their ranks have been swollen by black players over the last decade, Real Madrid, Barcelona and Spanish teams in general have been slow to address racism, compared with counterparts such as the Bundesliga in Germany or the Premier League in England, which has recently investigated comments made in games by Chelsea's John Terry and Liverpool's Luis Suárez. Allegations against England captain Terry for a racist slur have led to a police inquiry. Suárez received a £40,000 fine (about $60,000) and an eight-match suspension.

The biggest fine the Spanish Football Federation has levied at a club for racist behavior was a meager ¤9,000 levy (about $12,000) in 2006. It doled out the fine to Real Zaragoza. During a game against Barcelona, Barça's Samuel Eto'o was subjected to a chorus of ape noises from Real Zaragoza's stands. '¡No más!' he shrieked to the ref and fellow players, forcing a halt in play in the middle of the match, as he staged an abortive walkout. The previous year he had been pelted with peanuts at the ground.

"I remember," says Ramón Spaaij, a Dutch sociologist who spent six years embedded with soccer hooligans in Britain, Holland and Spain, "talking to some fans and what they were saying was, 'Look, when the black player is on our team, he's one of us. When he's with them, he's a black bastard.' It's neighborhood nationalism. You're on our team or you're on the other team, especially in a Barça-Madrid match.

"Someone like Samuel Eto'o in the past copped a lot of racial abuse from Real Madrid fans because not only is he black but particularly because he was a black Barcelona player. A lot of fans would say it wasn't meant in a racist way. It was just a 'joke': 'Ah, look, if we hurl enough racist abuse at this player, we might knock him off his game.' It's almost situational racism."

Racist abuse is not unique to the Spanish game. In June 2011, for instance, the Brazilian World Cup-winner Roberto Carlos walked off the pitch in protest during stoppage time in a Russian league game after a banana was thrown at him. Three months earlier, Zenit St Petersburg was fined $10,000 because a fan offered him a banana before a match.

In November 2010, a group of approximately 100 right-wing Italian fans racially abused their own player, 20-year-old Mario Balotelli, who was making his second appearance for his country in Austria. Balotelli was born in Italy to Ghanaian parents. While playing for his old club, Inter, rival fans from Juventus once wielded a banner for him that read: "A negro cannot be Italian".

"What I noticed is how widespread racism is on the terraces in Spain. It's similar to Italy," says Spaaij. "In England and the Netherlands, in contrast, where it still occurs it is usually concentrated in one section of the ground, or it involves a particular player or coach against another player or coach, like the John Terry-Anton Ferdinand case in England.

"In Spain, it can happen with a majority of the crowd, across age, gender and education. The serious racist abuse might start with the right-wing group, a team's ultras, but you will end up with monkey chants going all around the stadium. I've been at games where 80 percent of the stadium was chanting, including old men and women."

Both Barcelona and Real Madrid have long rap sheets of racist offences over the last 20 years. At Real Madrid, for example, shortly before the Argentinian Jorge Valdano was appointed manager in 1994, there was graffiti scrawled on the walls of the Bernabéu Stadium: "Valdano, stay in Africa," and "No to cross breeding, Valdano never." In 2004, UEFA fined the club because its fans racially abused Bayer Leverkusen players Roque Junior and Juan. In 2005, four members of the Ultras Sur were arrested for attacking a group of black North American students after a match against Juventus.

"There is racism in Spanish society at large, but it's unconscious,' says Giles Tremlett, an English journalist with the Guardian and author of Ghosts of Spain: Travels through a Country's Hidden Past. He lives in Madrid. "People are convinced they're not racist, but they are really, probably no more, no less than in any other country. Public expressions of it in soccer grounds here are [deemed] perfectly acceptable. They will call a black player a mono. They just haven't been through the process. Also they turn a blind eye; the refs don't report it; the press doesn't report it. They're on a different part of the curve."

Both Barcelona and Real Madrid have engaged in ad hoc initiatives. They promote anti-racist awareness in their soccer school foundations. Several of Barcelona's players ? Lionel Messi, Gerard Piqué and the Malian midfielder Seydou Keita ? recently appeared in a 30-second "Put Racism Offside" film. When their teammate, David Villa, signed with the club in May 2010, he set a precedent by including an anti-racism clause in his contract.

SOS Racismo commends these efforts, but says they are not enough. "Something more radical is needed," says José Peñín, a spokesperson for the organization. "All the players need to be involved in the cause and more than anything the teams' owners, directors and trainers."

The abdication of responsibility from the game's figureheads is noticeable. Barça played its Barcelona City derby at Espanyol's Cornellà-El Prat stadium in December 2010. Barça won 5-1. During the press conference afterwards, an English journalist form the BBC asked Guardiola, Barcelona's manager, about the racist chanting that was directed at his player, Dani Alves. It was ugly stuff and relentless throughout the match, with lone men springing to their feet to make their monkey sounds, scenes which were repeated in this season's corresponding fixture earlier this month.

"Sometimes it happens, at home and away. It's a very tough game. Forget it and keep going," said Guardiola, answering the question in English. It was another missed tackle.

Spain sits on top of the world when it comes to soccer. As well as being World Champions, its national team will seek to make history by retaining its European crown at the Euro 2012 finals this summer. Their possession-based, tiki-taka brand of soccer is the envy of youth academies around the globe. Why, at the moment the country should be basking in the glory of universal applause, is it tainted by outbreaks of racism? It is a situation that is particularly ironic in Barcelona's case, given its vaunted affiliation with UNICEF.

If there are any racist scenes at Wednesday's clásico match, hopefully Guardiola and Mourinho, his opposite number, will put the boot in.

Richard Fitzpatrick is an Irish journalist. He lives in Barcelona. His book, El Clásico: Barcelona v. Real Madrid, Football's Greatest Rivalry will be published by Bloomsbury in August.