Sergio Busquets will discover on Monday if he will miss Barcelona's Champions League final with Manchester United on 28 May after Uefa opened a disciplinary case against the midfielder regarding racist comments he allegedly directed at Marcelo during the semi-final first-leg victory over Real Madrid.

In a video posted on Real's website on the day before the second leg subtitles were provided which claimed to show Busquets calling Marcelo "mono, mono" (Spanish for "monkey, monkey") while he covered his mouth with his hands. Barcelona insisted on Thursday that he was saying "mucho morro", meaning "you've got a cheek".

The incident was one of several in a controversial tie, won 3-1 on aggregate by Barcelona, with both clubs lodging complaints with Uefa following the first leg. Madrid were unhappy at the behaviour of the opposing players and the red card shown to Pepe during the first leg, while Barcelona protested over the Madrid coach José Mourinho's post-match comments.

These called into question the Catalan club's relationship with the European governing body. Claims of favouritism were dismissed, and Mourinho was handed a five-game European ban for his remarks.

The governing body said: "Uefa has opened disciplinary proceedings against Barcelona midfielder Sergio Busquets, who is alleged to have violated article 11 of the disciplinary regulations by directing racist abuse towards a Real Madrid player in the Uefa Champions League semi-final first leg between the clubs on 27 April.

"The proceedings have been launched on the basis of evidence provided by Real Madrid [a video plus the statements from the club and player]. The control and disciplinary body will deal with the case on 15 May and the decision will be communicated to the club on 16 May."