The Spanish FA’s Competition Committee judge, Francisco Rubio Sanchez, said in a statement Madrid had fielded an “improper line-up” and the tie was settled “in favour of Cadiz”.
Marca earlier reported that Real Madrid will appeal to the RFEF and if necessary to Spain’s sport court, TAD.
Madrid president Florentino Perez said on Thursday the club would fight any sanctions for playing Cheryshev against Cadiz.
Cheryshev was withdrawn from the action moments after half-time, when Real had realised their error, with head coach Rafael Benitez saying they wanted to “show good faith”.
Perez believes that as neither the player nor the club were informed of the suspension that Real cannot therefore be disqualified from the Copa del Rey.
“The one-match ban for three yellow cards in our view is not effective because no one has notified the player as specified in item 41.2 of the disciplinary code of the RFEF,” Perez told a press conference.
Earlier, Cheryshev confirmed he did not receive notification from his former club that he would be banned.
He told his current club’s website, realmadrid.com: “I did not receive any notification from Villarreal to inform me that I had been banned from playing in the Copa del Rey.”
Last season Osasuna were kicked out of the tournament for playing an ineligible player, while Benitez was in charge of Valencia when they were disqualified from the Copa del Rey in 2001 having played too many non-EU players in a tie.