Marc-Andre ter Stegen saved a last-minute penalty as Barcelona beat Sevilla 2-1 to win the Spanish Super Cup in Tangier, Morocco.
In a statement released on Twitter, Sevilla made clear their objections to the decision: "Sevilla FC is surprised by the RFEF's statement 24 hours before the Super Cup".
According to the rule governing the game in Spain, only three non-EU players are allowed in each La Liga matchday squad.
Sunday's Spanish Super Cup final may not go ahead after Sevilla threatened to pull out of the match if Barcelona field more than three non-EU players.
Roque Mesa is among the players to come in for only his second start since his move from Swansea City, while Luis Muriel will lead the line for last season's beaten Copa del Rey finalists.
More news: Canada adds 54100 jobs in July, unemployment rate falls to 5.8%He has since won the Spanish title another eight times, while he has also helped the Catalans to Champions League success on four occasions - in 2006, 2009, 2011 and 2015. In their last notice for the 18-19 season, only three were due to be permitted, without exception.
"The club's legal department is studying the matter and should FC Barcelona submit a team with more than three non-EU players, it would present possible ground for withdrawal on account of an improper line-up".
There is also a debut for Arthur Melo in midfield, although Arturo Vidal and Malcom are forced to wait for their Barcelona bows, with the former being named amongst the substitutes alongside World Cup finalists Ivan Rakitic and Samuel Umtiti.
Philippe Coutinho has reportedly acquired a Portuguese passport through his wife in the last week, while his fellow South Americans Lionel Messi and Luis Suarez are already European Union citizens.
"I think that Sevilla are professionals and we are professionals".
