Cadiz president Manuel Vizcaino has confirmed his club will report Real Madrid to the Spanish Football Federation (RFEF) over their selection of Denis Cheryshev in Wednesday's Copa del Rey match.
Rafael Benitez's side won the first leg of the last-32 tie 3-1, with Cheryshev opening the scoring, but it emerged during the match that the Russian midfielder should have been serving a one-match suspension.
He collected three bookings while on loan at Villarreal during last season's competition, the last of which came in their final match against Barcelona in the semi-finals.
The ban should therefore have been carried over to the current campaign and Madrid substituted Cheryshev at half-time as speculation swirled.