Cristiano Ronaldo has since been criticised for his underwhelming performances not just against their rivals, but this season in general.
Los Blancos manager Rafa Benitez is similarly in the firing line of scrutiny after just a few months at the helm.
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And now, it seems Ronaldo has also expressed discontent with Benitez following their capitulation against the Catalonians.
Speaking to team-mates in the dressing room following the defeat, he said, according to the Telegraph: "Either he goes, or I go."
Defeat came as a heavy blow to the Spanish giants, who have lost for the second straight week in La Liga - and as a result, tempers are flaring in the capital.
Rumours were rife prior to Ronaldo's tirade regarding his future, the Portuguese linked with moves to Ligue 1 champions Paris Saint-Germain and Manchester United, which now seem all-the-more likely given his growing dissatisfaction at Real.
"PEREZ IS THE PROBLEM"
However, whether it be Ronaldo or Benitez's fault, fans are now calling for Real president Florentino Perez's head, insisting he is the true root cause of the club's struggles.
The unhappiness amongst fans was evident come the full-time whistle on Saturday, when spectators waved white flags.
The real question posed in the aftermath of Real's mauling is how long Perez will stay loyal to his strange ideal of pursuing the biggest names rather than seeking what's actually best for the team. He's hired and fired 13 managers in 15 years rather than opting for any kind of continuity, unlike their Catalonian counterparts.
The result? One La Liga title in the last seven years - a record one Champions League triumph cannot paper over.