Manchester United could eventually pay £61.5m to Monaco for Anthony Martial if all of the clauses in the deal are met, according to an alleged leaked document.
United have declined to comment on the document, which first appeared on website Football Leaks and claims to show the details of the French forward's move between the clubs in the summer transfer window.
The document says the initial fee of 50m Euros (£38.5m) for the player is to be paid in two instalments - €20m (£15.4m) within three days of his transfer, and €30m (£23.1m) on July 1.
There are then three further potential payments - €10m (£7.7m) if the player scores 25 first-team goals for Manchester United, €10m (£7.7m) if Martial makes 25 appearances for the French national team and €10m (£7.7m) more if the player is ever nominated for the Ballon d'Or award.
There is also a sell-on clause inserted in the deal, with Monaco due to be paid 50 per cent of any transfer fee between €60m and €100m United receive for the player.
Martial was the most expensive teenager in the world when Manchester United bought him in August, and he signed a four-year deal with the club.
The forward, who has scored eight goals in 26 appearances so far this season, had signed a new deal with Monaco in June, when the Ligue 1 club's vice-president Vadim Vasilyev called the player "untransferable", only for him to move less than two months later.