Atletico Madrid have been hit with a €12,000 fine after supporters targeted Barcelona forward Antoine Griezmann during their LaLiga clash in December.
Griezmann, 28, completed his protracted move to Barca from Atletico last summer.
The France forward had looked set to move to Camp Nou in 2018, only to reaffirm his commitment to Atletico in a now-derided TV documentary titled 'The Decision'.
The documentary irked Atletico fans, and the World Cup winner's eventual €120million move to Barca was an acrimonious one as Atleti threatened legal action over what they perceived to be an illegal approach from Barca.
On Griezmann's return to Madrid in Barca colours, Atletico fans sang "Die Griezmann Die" - and the club have now been fined by the Spanish Football Federation (RFEF).
A statement from the RFEF's competition committee on Wednesday confirmed the fine for the chanting, following a complaint from LaLiga.
The referee's report from the game on December 1 - which finished 1-0 to Barca courtesy of a Lionel Messi goal - did not make any reference to the chanting.
The league's organising body has been cracking down on offensive chanting since a Deportivo La Coruna fan died following violence before a game away to Atletico in 2014.
Additional reporting by Reuters.
