Did Real Madrid violate the regulations by including Mastantuono?

Argentine youngster Franco Mastrantuono made his Real Madrid debut against Osasuna on Tuesday evening at the Santiago Bernabéu in the first round of the Spanish League, a match won by the royal team with a goal scored by Kylian Mbappé from the penalty spot. Real Madrid signed the 18-year-old Mastrantuono during the current summer transfer window, coming from Argentine club River Plate, on a contract that runs until 2031. However, his participation in the match sparked legal controversy, after the Spanish newspaper "AS" indicated that the player was registered with the reserve team "Castilla", which raised questions about the legality of his participation with the first team, especially with the transfer window closing on September 1. According to Miguel Galán, president of the National Center for the Training of Football Coaches (CENAFE), Mastrantuono's participation could constitute a potential violation of the lineup, and Osasuna has up to 24 hours after the end of the match to file an official complaint against Real Madrid. Although registering a player with the reserve team is not in itself a violation, his actual participation with the first team reopens the controversy, especially if it is proven that the registration was done to circumvent the rules. Some legal opinions suggest that Real Madrid may have acted in bad faith by registering the player with the reserve team, even though he had been officially introduced to the first team. Experts believe this move may be an attempt to circumvent the 25-player limit on the first team, which could constitute a violation of Article 125 of the Spanish Football Federation's General Regulations, which prohibits the use of the relationship between the first team and the reserve team as a means of circumventing regulations.