Athletic Club fans mocked Barcelona by throwing fake money on to the pitch amid the corruption scandal surrounding the club over referee payments.
Athletic Club supporters threw banknotes with Barca's badge printed on them and "Mafia" written in large capitals with a dollar sign next to it during the Liga clash between the two clubs at San Mames on Sunday night.
The protest occurred in the wake of the confirmation that Barca are being investigated over payments made to the former vice-president of the Technical Committee of Referees (CTA), Jose Maria Enriquez Negreira.
It may be a long time before the case against Barcelona is resolved as the potentially lengthy legal process has just begun