Real Madrid accuse Barca and Busquets of racism

As Barcelona prepare to welcome Real Madrid to the Camp Nou for tonight's Champions League semi-final second leg the world waits with bated breath to see if the game descends into another slugfest - and with allegations of racism now flying around who would doubt it?

The poisonous atmosphere between the two clubs has not been helped by footage that appears to show Barcelona midfielder Sergio Busquets racially abusing Real Madrid full-back Marcelo.

The clip, that has been released by Real on their official TV Channel, shows Busquets apparently mouthing the words 'mono, mono'  [monkey, monkey] at Marcelo. Barcelona have yet respond to the claim, nor have Uefa, who have promised in recent years to stamp out racism in all forms.

But the allegations bring a dramatic new twist to the ongoing feud between the clubs and could prove very damaging to Barcelona, who have been anxious to portray themselves as the wronged party in the recent rows.

With Real Madrid manager Jose Mourinho taking a break from his job of baiting Barcelona it fell to assistant boss Aitor Karanka to ratchet up the tension on Monday. Referring to the Busquets incident and the suspension of two Madrid players and Mourinho from the game in Barcelona, he said: "We have been punished, but there are players who didn't respect the principles of fair play or who made racist insults, covering their mouths, who will be on the pitch."

Barca coach Pep Guardiola leapt to the defence of his players, announcing: "Mourinho was here for five years and he knows our values: to win, fight and earn respect by respecting your rival... They think we are unsporting, but I think completely the opposite. Here we teach our players manners from a young age."

On the pitch, Barca go into the game with a two goal advantage from the first leg, thanks to Lionel Messi's double strike last week in what's since been dubbed the 'Battle of the Bernabeu'.

Real had defender Pepe sent off for a dangerous tackle, while Barcelona's reserve keeper, Jose Pinto, was shown red for his part in a half-time skirmish. On top of that Mourinho was also sent off for bad mouthing the officials and he will have to watch tonight's game from the stands.

Both Barcelona and Real Madrid made official complaints to Uefa about one another's conduct at the Bernabeu, protests that on Monday were rejected by the governing body. However, the two clubs are still facing sanctions from Uefa following the fiery tie and will learn their fate on Friday when they appear before a disciplinary board to answer charges of misconduct.

Barcelona president Sandro Rosell used a press conference on Monday to call on fans to "show good manners and common sense", adding: "Our supporters are a model of good behaviour and I am asking them to show that again this Tuesday, especially because all eyes will be on us. I want them to support the team, forget about all the other stuff and not get provoked."

However, there could be more trouble on the horizon after Uefa appointed Frank de Bleeckere as tonight's referee.

The 44-year-old Belgian is rated one of the top whistle-blowers in the game, though not by Mourinho. He was livid last year when – as coach of Inter – he saw midfielder Thiago Motta sent off by de Bleeckere during a Champions League semi-final... against Barcelona. The incident clearly rankles still with Mourinho for when he alleged last week that Barcelona received preferential treatment from referees, de Bleeckere was one of the officials he fingered in his conspiracy theory. ·