Real Madrid's Ronaldo has been granted Spanish citizenship, meaning he will no longer take one of the club's three berths for non-European Union players.
The Brazil striker, who joined Real from Inter Milan for 43 million euros (29 million pounds) in 2002, secured dual nationality after taking an oath to the Spanish constitution on Thursday.
According to Spanish Football Federation (RFEF) rules, each Primera Liga club is allowed a maximum of three non-European Union players on their books.
With Roberto Carlos gaining Spanish citizenship in August, the only two Real players that do not enjoy European Union status are Brazilian forwards Julio Baptista and Robinho.
Real will thus be free to buy a non-European player in the January transfer window to strengthen their squad. They already have an option to sign Brazil defender Cicinho from Sao Paulo.
Ronaldo suffered a partial ligament tear in his left ankle in last month's 3-0 league win over neighbours Atletico Madrid.
The 29-year-old faces a race against time to recover for the showdown with arch-rivals Barcelona on November 19.
