Sporting Lisbon are facing a financial shortfall after payments for Bruno Fernandes were blocked by a German bank, reports in Portugal claim.
The Portuguese club finally agreed to sell their captain to Manchester United in the January transfer window after agreeing a hefty fee.
United agreed to pay an initial fee of £47million, with add-ons potentially taking the fee for the player up to £67.6m in the future.
But O Jogo claim that Sporting wanted the initial £47m up front, whilst United only agreed to pay in equal installments over a four-year period.