Uefa has launched a disciplinary case against Barcelona's Sergio Busquets over alleged racism in the Champions League semi-final with Real Madrid.
Real posted a video on their website before the second leg showing Busquets allegedly calling full-back Marcelo "mono" (monkey) in the first leg.
The case will be heard on Sunday with a decision due the next day.
The incident was one of several in a heated tie between the Spanish rivals, which Barca won 3-1 on aggregate.
Both clubs lodged complaints to European football's governing body after an ill-tempered first leg at the Bernabeu, which was won 2-0 by Barcelona.
Madrid were unhappy with the behaviour of the opposing players and the red card shown to midfielder Pepe (one of three dismissals during the game, along with Barca reserve goalkeeper Jose Pinto and Real coach Jose Mourinho).
Barca protested over Mourinho's post-match comments alluding to favours from Uefa in big Champions League games and questioning the Catalan club's relationship with the European governing body.
The complaints were dismissed by Uefa, with Mourinho later handed a five-game European ban for his remarks.
The former Chelsea and Inter Milan boss chose not to speak to the media ahead of the second leg of the semi-final at the Nou Camp, which finished 1-1, thus booking Barca's place in the Champions League final at Wembley, where they will play Manchester United.
Instead, it was left to Mourinho's assistant Aitor Karanka to bemoan Uefa's decision not to act on Real's claims of gamesmanship by Barcelona's players.
He said: "The match has been overshadowed by Uefa's resolution - it's on another plane now.
"We have been punished [with the suspensions for Pepe, Sergio Ramos and Mourinho], but there are [Barcelona] players who didn't respect the principles of fair play or who made racist insults, covering their mouths, who will be on the pitch.
"We say over and over there are double standards."
However, Barca coach Pep Guardiola countered by defending his players.
"My players are an example of professionalism and honesty," he said.
"Real might think we are unsporting but I think exactly the opposite. Fourteen of 20 players in the squad have grown up in this house and they all respect the values of the house.
"Mourinho was at Barcelona for five years and he knows our values: to win, fight and earn respect by respecting your rival."