Manchester United reportedly have to pay Monaco a further £8.7m after Anthony Martial struck his 25th Premier League goal for the club.
The France international swapped sides three years ago for an upfront fee of £36m, although that figure could potentially climb to £45m.
According to The Telegraph, Martial's 76th-minute equaliser in the eventual 3-2 win against Newcastle United last weekend, taking him to the quarter-of-a-century mark in the English top flight, triggered the latest clause in the forward's contract.
Martial had been stuck on 24 league goals for more than eight months, with his most recent strike before Saturday coming against Burnley on January 20.
However, the same report suggests that Monaco have missed out on a further windfall as the 22-year-old will not rack up 25 appearances for the France senior side before the end of this season.
