Manchester United are due to make an inflated payment of £8.5million for Anthony Martial when he scores another four goals.
One of the many add-ons in the deal, which could total €80million, was that United would have to pay Monaco €10million once the player scored 25 competitive goals.
The 20-year-old blasted 17 goals in a brilliant debut season, but his form has slowed down this term. However, he scored twice against West Ham in the EFL Cup on Wednesday night taking his tally to 21 goals.
That means Monaco are closing in on another installment, but due to Brexit the £7million they thought would be due is now almost £8.5million.
United, who paid a second €30million installment in the summer, also face a further €10million once Martial hits 25 France caps and with the striker on 15 to date, although he was recently axed from Les Bleus squad for their games against Sweden and Ivory Coast.
United stole the headlines on transfer deadline day in August with the big-money capture of young forward Martial.
The deal was understood to include a number of performance-related add-ons and a file which first appeared on Football Leaks has brought to light the details of the transfer.
France international Martial initially cost the Red Devils a transfer fee of €50million, which has been paid over two installments.
Additionally, United will need to pay the French club another €10million if the striker scores 25 goals in competitive matches.
A further €10million will be owed if the 20-year-old earns 25 France caps, although each appearance needs to be at least 45 minutes long.
The same amount must be paid again if Martial is nominated for the Ballon d’Or.