Chelsea are set to sign Real Madrid midfielder Mateo Kovacic for £40m despite tbeing under a two-year transfer ban.
Kovacic spent last season on loan at Stamford Bridge, so Chelsea have already registered him.
It means, providing the deal is done before the loan expires on 30 June, it would not require another registration.
Therefore, that would not contravene Fifa's transfer ban on Chelsea, which runs until the end of January 2020.
The suspension is currently the subject of an appeal to the Court of Arbitration for Sport.