Real Madrid have been thrown out of the Copa Del Rey and fined for fielding an ineligible player, but they are appealing the decision.
Russia winger Denis Cheryshev started in the fourth-round tie, despite being suspended after picking up a third yellow card in the semi-finals of last season's competition when on loan at Villarreal, and scored Real's first goal.
Cheryshev was withdrawn from the action moments after half-time when Real had realised their error, with head coach Rafael Benitez saying they wanted to "show good faith".
Spain's football federation said Friday Real Madrid had fielded an "improper lineup" and that the two-match series was settled "in favour of Cadiz". They have been fined 6,000 euros (£4315) but the 19-time Cup winners have said they will contest the decision.
Their statement, issued on Friday evening, read: "We have received the decision of the competition committee chief and the club has come to the conclusion that it is acknowledged the RFEF (Spanish FA) has not personally notified the player Cheryshev, which is the only way for a sanction to take effect, as per article 41.2 of the disciplinary code.
"Real Madrid confirm it will take the necessary steps and is confident the final verdict will be favourable to the club."
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 having played too many non-EU players in a tie in 2001.
Guillem Balague told Sky Sports News HQ that he does not believe Real's appeal will be successful.
The Sky Sports Spanish football expert said: "This is massive news in Spanish football. Perez insisted they would appeal because they've done nothing wrong. They will appeal to the competition committee but they will say 'no, you're wrong'.
"You never know with the committee, but the rules are clear. I don't think there's an escape here."
With the controversial exit of goalkeeper Iker Casillas, the last-minute failure to sign Manchester United 'keeper David de Gea and now their Copa del Rey demotion, Balague says the club's president is coming under increasing fire.
On the damage to Real's reputation, he added: "There was Casillas, De Gea - maybe it wasn't the fax machine! - and now this.
"It looks really bad for Real Madrid even though they keep saying they've done nothing wrong and they are running the club properly. A lot of people are questioning this. Everybody is looking at Florentino Perez."
Perez made a passionate plea in Thursday's press conference, emphasising the feeling of injustice of the situation and the club's desire to contest being kicked out of the country's famous competition.
On playing the ineligible Cheryshev, Perez said: "Nobody told the club or the player, not the federation nor Villarreal, so it was impossible for us to act differently. It's not our fault.
"What happened last night has never happened to Real Madrid before. If we didn't know, the sanction cannot stand.
"We checked the situations of all of the players listed in the squad rigorously before yesterday's game. Look, in the football section, there is a department dedicated solely to these kinds of issues; no-one told them about Cheryshev.
"Sanctions cannot be enforced unless the player is personally notified, that's the way I understand it."
Watch highlights of Real Madrid v Getafe in La Liga on Sky Sports 2 HD on Saturday, 9.30pm