Chelsea have taken their appeal against a two-window transfer ban imposed by Fifa to the Court of Arbitration for Sport.
The Blues are not allowed to buy players until the end of January 2020 and failed with their first appeal to the world governing body.
It followed an investigation into their signing of foreign under-18 players.
The transfer window closes on 8 August and Cas said “it is not possible” to say when it will make a decision.
Chelsea have not asked for the ban to be lifted while Cas considers its decision. The Blues are also appealing against their £460,000 fine.