Barcelona said on Thursday they will make a complaint to Spanish sporting authorities over comments by Malaga's Qatari owner Abdullah Al-Thani on Twitter describing the Catalans as "scum".
"FC Barcelona expresses its rejection and indignation at the content of the tweet published by the president of Malaga, Abdullah Al-Thani, which is counter to the principles of fair-play, ethics and legality," said the Spanish champions in a statement.
Al-Thani had responded to a message on Twitter from a Barcelona fan asking his club to do them a favour by beating Real Madrid on the last day of the season.
"God willing they (Real) will be flogged on the pitch. But the scum of Catalonia will not smell the league (title) after the lies they made up about coach Michel," said the Qatari sheikh.
Malaga are coached by former Real player Michel who has come under fire in the Catalan press, questioning whether he would rather his side lose to Real so his ex employers can win the league.
Michel himself had said he'd rather provide Real with a "guard of honour" than a "blow" when the European champions visit the Rosaleda on the final day of the season.
However, he added: "But I'm a winner and I hope that before the final day everything is decided."
Eternal rivals Real and Barca are level on points with less than a month of the season left.
Real have a game in hand on Barca, who went top of la Liga by winning 3-2 at the Santiago Bernabeu on Sunday.