LEAKED: The huge add-on fees Anthony Martial could cost Manchester United revealed in official transfer papers

Anthony Martial became the world's most expensive teenager when he signed for Manchester United.

But the world didn't truly know how expensive the then 19-year-old Monaco striker was...until now. Reports said the young French international cost United around £36m. However, Le Figaro has leaked official transfer papers between the Ligue 1 club and the Red Devils and it shows just how much Martial could come to cost them after add-ons. Over the course of the season the papers show United agreed to pay €50m (£38m) for the star. But they will have to stump up another €10m (£7.6m) if he scores 25 league goals, €10m if he wins 25 caps for France and €10m if he is nominated for the Ballon d'Or award. That could total upwards of £60m. But it also details that if United sell Martial for more than €60m (£45m), then Monaco will get half of the capital gains as part of the deal. Here is the contract in full...