Middlesbrough have reportedly been ordered to pay €1million following a FIFA hearing.
According to reports in Spain, Boro have been told to stump up the sum following the signing of Spanish striker Kike Garcia in 2014.
The frontman was signed from Murcia for an initial fee of €2.5million, with an additional €1million payable if the club were promoted to the Premier League.
But despite initial success, Garcia struggled for opportunities and made the move back to his homeland in 2016 - teaming-up with Eibar.
The signing was completed on February 2nd, meaning Garcia was unable to be registered for the remainder of that season as the deadline was missed.
At the end of the campaign, Boro secured promotion to the top flight and Murcia came knocking for their additional €1million - claiming the player was still registered with the club given he could not be signed-on for Eibar.
Middlesbrough, though, disagreed and felt that the player was no longer theirs and so the fee should not be payable.
Murcia decided to take the case to FIFA who, according to these fresh reports, have ruled in their favour.
That means Boro will have to pay the seven-figure fee to the Spanish side within 30 days.
Garcia, signed by Aitor Karanka, made 53 appearances at the Riverside Stadium and scored 15 times.