Atletico Madrid are waiting to find out if they will be allowed to sign new players in June after pleading their case over a FIFA-imposed transfer ban at the Court of Arbitration for Sport on Monday.
"Only the lawyers are present and no decision will be made today (Monday)," CAS secretary general Matthieu Reeb told AFP.
Atletico and city rivals Real Madrid were barred from registering new players for two transfer windows in January 2016 for irregularities in the signing of foreign players under 18.
Both clubs saw initial appeals rejected by FIFA last September, although CAS reduced Real's sanction in December allowing the European champions to recruit new players as of this summer.
Atletico president Enrique Cerezo is hopeful sport's highest court will grant his club a similar ruling and halve their initial two-window ban.