Sporting Lisbon are reportedly waiting to collect a further payment of £9million from Manchester United as part of the deal that took Bruno Fernandes to Old Trafford in January.
The Portuguese midfielder made a sensational £68m move earlier this year and has slotted into United's midfield effortlessly, becoming a key part of Ole Gunnar Solskjaer's plans.
It is believed Sporting let him go for an initial £47m, which could rise to £68m depending on whether a series of bonuses are met.
According to Portuguese newspaper A Bola, one of those is for £4.