Manchester City's appeal against their two-year ban from European club competition has been registered by the Court of Arbitration for Sport (Cas).
The Premier League champions were also fined 30m euros (£25m) for "serious breaches" of Uefa's financial regulations.
City chief executive Ferran Soriano has said the breaches are "simply not true".
Cas says "it is not possible" to say when the matter will be resolved.
Cas arbitration procedures involve an exchange of written submissions between the parties while a panel of arbitrators is convened to hear the appeal.
The independent adjudicatory chamber of the Club Financial Control Body (CFCB) said it found City had broken the rules by "overstating its sponsorship revenue in its accounts and in the break-even information submitted to Uefa between 2012 and 2016", adding that the club "failed to cooperate in the investigation".
At the time, City said they were "disappointed but not surprised" by the "prejudicial" decision and would appeal.
Uefa launched an investigation after German newspaper Der Spiegel published leaked documents in November 2018 alleging City had inflated the value of a sponsorship deal, misleading European football's governing body.
Reports alleged City - who have always denied wrongdoing - deliberately misled Uefa so they could meet financial fair play rules requiring clubs to break even.