Chelsea have signed Croatia midfielder Mateo Kovacic from Real Madrid for £40m, despite being under a two-window transfer ban.
Kovacic spent last season on loan with the Blues, helping them win the Europa League, and joins on a five-year deal.
Chelsea had already registered the 25-year-old when he was on loan and did not require another registration.
The transfer ban issued by world governing body Fifa runs until the end of January 2020.
The suspension, which followed an investigation into the Stamford Bridge club’s signing of foreign under-18 players, is being appealed against at the Court of Arbitration for Sport.
Chelsea have not asked for the ban to be lifted until the appeal is heard.
Kovacic made 32 Premier League appearances for the Blues last season, although former manager Maurizio Sarri regularly switched him with England midfielder Ross Barkley.
Chelsea are expected to confirm Derby County boss Frank Lampard as Sarri’s successor in the coming days.
