Osasuna is thinking about challenging Barcelona’s win on Thursday, March 27, because of a possible ineligible lineup involving Iñigo Martínez. According to FIFA rules, a player who withdraws from international duty due to injury can't play for his club for five days after the last game of the international break. In this case, Spain played their last match on March 23, meaning Martínez only rested for four days before returning to action.

The key: Federation approval

FIFA's Article 5 states that if a player pulls out of the national team due to injury, he can't play for his club for five days unless his national federation gives the green light. Now, the big question is whether the Spanish Football Federation (RFEF) granted that permission to Martínez, which would clear Barcelona of any wrongdoing.

Martínez missed out on Spain’s squad because of a knee issue he picked up in a match against Atlético de Madrid. Luis de la Fuente replaced him with Dean Huijsen. However, the defender continued his recovery in Barcelona and was back in training on Monday before starting against Osasuna.

Possible consequences for Barcelona

Osasuna has put its legal team on the case to see if they have grounds for an official complaint to the RFEF. If Barcelona is found guilty of fielding an ineligible player, they could face a punishment and lose the match by default.

The game, part of LaLiga's Matchday 27, was played at Montjuïc and ended in a win for the Blaugrana. Despite the international break affecting squad availability, Flick decided to start Iñigo Martínez, sparking this whole controversy.

Now, it all depends on how FIFA and the RFEF interpret the defender’s situation. While Osasuna considers its next move, Barcelona is confident that the Federation’s approval will keep them out of trouble.