Real Madrid could be kicked out of the Copa del Rey after fielding an ineligible player in the first leg of their fourth-round tie at Cadiz.
Madrid named winger Denis Cheryshev in their starting XI for the 3-1 win at the Segunda B club, but reports in Spain claim he should have been suspended for the game having been booked three times in the competition on loan at Villarreal last season.
The booking which triggered the suspension was picked up in the second leg of Villarreal's 6-2 defeat to Madrid's arch-rivals Barcelona in last season's semifinals.
RFEF rules give the governing body the power to throw Los Blancos out of the competition. Osasuna were removed from this season's Copa del Rey in September after fielding Unai Garcia -- who had been sent off against Alaves last season -- in a 2-1 victory win over Mirandes.
Cheryshev scored the opening goal of the game after three minutes against the third-tier Andalusian side, but news soon spread around the Ramon de Carranza that led to Cadiz fans chanting the Russian winger's name.
He was withdrawn by boss Rafa Benitez early in the second half, being replaced by Mateo Kovacic, after the club were made aware of the error. It is reported that Madrid wrongly thought there was an amnesty at the end of last season which scrubbed Cheryshev's ban.
Buenos días! No prizes for guessing what's on the front page today.. Cock-up in Cádiz leaves RM facing elimination.. pic.twitter.com/aRVvjXgsv2
- AS English (@English_AS) December 3, 2015
Speaking after the game, Cadiz president Manolo Vizcaino said his club will make a formal appeal.
"The circumstances require a quick decision," Vizcaino told reporters. "The board has decided to make the complaint about the illegal lineup including the player Cheryshev. We have decided to do it, with pain in our heart, as Madrid as a club are our friend. But a firm and unanimous decision has been taken."
For his part, Real boss Benitez insisted he and the club were unaware of Cheryshev's situation, and weren't informed until after half-time.
"Clearly, the club did not know anything, the federation had not said anything, neither had Villarreal, so we thought we could field him," Benitez said. "As soon as we were aware, after half-time, we substituted him immediately to show good faith."
Madrid's director of institutional relations Emilio Butragueno echoed his coach's sentiments, repeatedly stating a lack of warning from the federation.
"It has been a difficult night, only thing we can say is that we did not receive any notification from association, or from Villarreal, where he received those cards," Butragueno said.
"Cheryshev did not know either about this possible ban. We will wait and see what happens, in any case it would be the competition judge who would decide, on Friday. We will wait and see what happens in hours to come. I spoke with the federation, who said we had to wait on the judge. But we do not know anything as we never received any notification of any punishment.
"I have spoken with Rafa, he asked, logically, as he was wondering what was happening. But again, nobody at Real Madrid had any notification, so Cheryshev could play. It is possible that, in the moment, when Cheryshev received yellow card for Villarreal, they received the communication. But nobody told us anything about it."
Butragueno, speaking to reporters in the mixed zone, later added: "Article 41 of the disciplinary code affirms that the possible punishment does not have effect if the interested party is not notified personally. The player did not know about the situation. At Madrid nobody knew anything, the player knew nothing either. That's why he played. Our legal services may have something to say, but we can say little else at this time."
It would not be the first time Benitez has had one of his teams thrown out of the competition. Valencia were also expelled in 2001 for playing four non-EU players in an early round tie against third-tier Novelda.
Barcelona defender Gerard Pique quickly tweeted mocking the error.
- Gerard Piqué (@3gerardpique) December 2, 2015
The second leg is scheduled to take place at the Bernabeu in two weeks' time.