Chelsea newcomer David Datro Fofana is the subject of a legal dispute between two other clubs over the Ivory Coast international's move to Norway two years ago.
The Court of Arbitration for Sport said Thursday it has registered a case filed by Ivorian club Abidjan City against Fofana and Norwegian club Molde.
Norwegian soccer magazine Josimar reported that Abidjan is alleging that it had Fofana already under contract when he signed for Molde, and that the club was not compensated for the transfer.
"The parties are exchanging written submissions," the court based in Lausanne, Switzerland, said in a statement, adding "a hearing date has not been set yet."
It was unclear what sanctioning powers CAS could have, though one option is sending the case back to FIFA for review. In breach of contract cases, FIFA can impose bans on players and clubs, who can be blocked from registering new players.
The legal dispute will likely not affect Chelsea, which announced the 20-year-old forward's signing last week, reportedly for about 12 million euros ($13 million) on a contract that runs into 2029.
Fofana scored 15 goals in helping Molde win the league title last year, earning entry into the Champions League qualifying rounds next season.
Chelsea said in a statement last week that Fofana had joined Molde "from the Amadou Diallo Football Academy in his homeland at the start of the 2021 campaign in Norway."
However, Abidjan City officials told Josimar that that Fofana had signed for the club as a 16-year-old, with his mother also signing the contract. His family later claimed those signatures were forgeries and that he was not under contract with Abidjan, Josimar reported.
The case previously passed through a FIFA transfer dispute panel.
Fofana made his debut for Chelsea on Sunday in a 4-0 loss against Manchester City in the FA Cup.
His new club said the forward's "combination of pace, skill and strength make him a versatile striker, capable of scoring goals but especially adept at holding up the ball and retaining possession under pressure."
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