Record says Sporting will only give Doyen €3 million from the cut of Rojo's fee - which is the amount the investment firm paid to help the Lisbon giants sign the player from Spartak Moscow.
Doyen insist they are due 75 per cent of any fee generated from Rojo's sale - which would be the equivalent of €15 million.
They are now taking the case to the Court of Arbitration for Sport.
For their part, Sporting insist they had ended their contract with Doyen before selling Rojo to United.
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