The Spanish Players' Union will report Rayo Vallecano to the Spanish government for not having a doctor for Sunday's defeat to Athletic Bilbao.
Real Madrid survived a late surge from Rayo Vallecano to win 2-1 at the Bernabeu on Satuday and maintain their spot at the top of LaLiga.
Barcelona have suffered back-to-back defeats in LaLiga as they slumped to a 1-0 loss at Rayo Vallecano on Wednesday.
Radamel Falcao has joined Rayo Vallecano on a free transfer after his contract with Galatasaray was terminated.
Erik Lamela enjoyed an ideal debut with Sevilla as he scored twice in a 3-0 win at home to Rayo Vallecano in his new side's first game.
Rayo Vallecano is returning to La Liga after a 2-0 win against Girona on Sunday.
Barcelona needed a second-half comeback to beat Rayo Vallecano in the Copa del Rey round of 16 and advance to the quarterfinals on Wednesday.
Spanish football returned in bizarre circumstances with the second half of a second-division match that first kicked off six months ago.
Rayo Vallecano have been punished with a two-game partial stadium ban and fined €18,000 because of the "Nazi" chants at Albacete's Roman Zozulya.
A Spanish second division football match was abandoned after fans subjected Roman Zozulya to offensive chanting and accused him of being a Nazi.