Barcelona's Mexican-born defender Rafael Marquez obtained dual Spanish citizenship on Friday, freeing the club to sign another player from outside the European Union.
Spanish Football Federation rules allow Primera Liga clubs only three non-European Union players in their squads. Barca's other two are Brazilian Ronaldinho and Cameroon striker Samuel Eto'o.
"It's good news for us because we now have the opportunity to try and fill that place, but we are not going to rush into a decision," Barca coach Frank Rijkaard told a news conference on Friday.
With forwards Eto'o, Lionel Messi and Javier Saviola all sidelined with injuries speculation has focused on the possibility of Barca looking to sign a player in the January transfer window.
One option being touted in the press is for the club to promote highly rated Mexican youngster Giovanni dos Santos from the youth teams to the first team.
The European and Spanish champions, who top the Primera Liga by a point from Sevilla, play Villarreal at home on Saturday.