Sevilla has threatened to file a complaint should Barcelona attempt to pick more than three players from outside the European Union in the Supercopa de Espana.
Ernesto Valverde has criticised the Royal Spanish Football Federation (RFEF) for announcing the Supercopa de Espana is categorised as a friendly.
Real Madrid beat Barcelona 3-1 in the Supercopa de Espana first leg thanks to Cristiano Ronaldo's wondergoal, but the Portuguese super star failed to finish the match.
Barcelona secured a 5-0 aggregate win over Sevilla in the Supercopa de Espana as Arda Turan hit a double in a 3-0 triumph at Camp Nou.
Athletic Bilbao has won its first silverware since 1984 after drawing 1-1 against Barcelona at Camp Nou, clinching the Spanish Super Cup 5-1 on aggregate.