Atletico Madrid will not be able to sign any players in January 2017 after agreeing to waive their right to suspend a FIFA transfer ban while they appeal the sanction.
Along with city rivals Real Madrid, Diego Simeone's side in September lost their initial appeal against a two-window suspension from registering new players for breaching the rules over the transfer of foreign players under the age of 18.
Atletico have petitioned the Court of Arbritration for Sport (CAS) to intervene and maintain their innocence, but agreed to waive their right to suspend the ban for next January's window while waiting for the case to be heard.
The agreement between the club and FIFA means CAS will give a final decision on the matter by June 1, 2017, and could result in Atletico being able to sign players in the close-season if they are successful in getting the punishment reduced.
FIFA released a statement on Thursday which read: "In the appeal proceedings before the Court of Arbitration for Sport (CAS) in relation to the decision notified by the FIFA Appeal Committee on 8 September 2016 imposing inter alia a transfer ban on Atletico Madrid, both parties have agreed on a procedural calendar in order to allow the CAS to render a final reasoned award by 1 June 2017.
"Atletico Madrid waived its right to seek suspensive effect of the appeal for the next winter transfer period following its initial request for the proceedings to be concluded by the first semester of 2017 and FIFA's subsequent request for said waiver.
"Even though Atletico Madrid completely maintains its position that the transfer ban is unjustified, it has decided to waive its right to seek suspensive effect for the next winter transfer period so as to ensure a procedural calendar that allows Atletico Madrid to fully present its case, while giving the panel sufficient time to thoroughly review all documents, consider all arguments and finalise the reasons before rendering its award.
"Due to the confidentiality of the proceedings, the parties will not make any further comments on the arbitration prior to the final award being rendered."
The punishments were originally handed out in January 2016.