Real Madrid president Florentino Perez has claimed that the club will not lose their place in the Copa del Rey.
Denis Cheryshev started for Real in their 3-1 win over Cadiz on Wednesday, but it soon emerged that the midfielder should have missed the game due to a suspension he picked up while on loan at Villarreal last season.
Clubs have previously been eliminated from the competition for making similar errors.
"The penalty Cheryshev was given while playing for Villarreal is ineffective in our view, no-one had mentioned the sanction to the player," Perez told reporters.
"As Article 41 of the RFEF's disciplinary code states, the punishment is not effective unless it notifies those to be punished.
"Real Madrid did not know of its existence, no-one reported it - neither the player nor Villarreal nor the RFEF."
Cadiz have filed an appeal to the Spanish Football Federation and an announcement is expected on Friday.
Callum Mulvihill
