Atletico Madrid's hopes of buying new players this summer have been dashed after the Court of Arbitration (CAS) for Sport upheld Fifa's transfer ban on the club.
The decisions has potentially large implications for the European transfer market this summer, throwing doubt on high-profile transfers in and out of the Spanish club.
Atletico Madrid said the ban, which restricts them from registering any new players until January 2018, "causes irreparable damage to our club".
The Champions League semi-finalists were sanctioned by Fifa last year after breaching rules on the transfers of players under the age of 18.
Unable to buy new players, Atletico may now be compelled to make a renewed effort to keep star forward Antoine Griezmann — a Manchester United target.
Lyon striker Alexandre Lacazette had been set to join the Spanish club this summer in time for their first season at the new 68,000 capacity Estadio Wanda Metropolitano.
Despite blasting the Fifa ban as discriminatory and unfair, Atletico insist they have contingency plans in place.
"Our sports planning for next season has contemplated at all times the two scenarios that could arise once CAS announced their decision," said Atletico Madrid in a statement.
"From this moment on, the club will move forward in the negotiations necessary to formalise the operations to register players from January 1, when we will be authorised by Fifa to register new licenses.
"The club has the commitment of the players and coaching staff to continue competing at the same level next season, despite this decision that is evidently detrimental to us."