Per the La Liga rulebook, which was thought to be applied to Sunday's game, clubs are only allowed to name three non-EU players in their matchday squad.
Barcelona signings Malcom, Arturo Vidal and Arthur will more than likely be Barca's three non-EU players on Sunday, though Brazilian centre-back Marlon has also travelled with the team.
La Liga gaints Sevilla have threatened to boycott their Super Cup encounter against Barcelona on Sunday if they name more than three non-European Union players for the match.
Sevilla qualified for the match as last season's Copa del Rey runners-up, after Barcelona won the league and cup double.
A Sevilla club statement read: "Sevilla FC is surprised by the RFEF [Spanish football federation]'s statement 24 hours before the Super Cup". Sevilla are upset about various matters, including: the match being played in Tangier, that it's a one-off match and most recently because of the RFEF confirming there's no limit as to how many non-EU players can be used.
"The club's legal department is studying the matter and should FC Barcelona line up with more than three non-EU players, it would present a possible ground for filing a complaint due to an improper line-up".
The victor of the match that will be staged in Tangier, Morocco, will be decided over one leg for the first time.
It was reported earlier this week that Barcelona were in the process of acquiring a Portuguese passport for midfielder Philippe Coutinho in order to free up a third non-EU playing spot in their squad and that process is believed to have been completed.
Despite the adjustment potentially giving his side an edge, Barca boss Valverde is also far from content.
"I think that Sevilla are professionals and we are professionals".
The Argentina global takes over from Iniesta following his move to Vissel Kobe in the J League at the end of the 2017-18 campaign.