Monaco vice-president Vadim Vasilyev has confirmed that Manchester United are likely to pay up to £57.6 million for Anthony Martial.
There had been some confusion over the price the Red Devils stumped up for the 19-year-old on deadline day, with the English press reporting a base figure of £36m.
However, Vasilyev has confirmed that the deal includes bonuses that are easily attainable and that United trebled their offer for the teenager in one week.
"The price for Martial is £57.6m but take into account this sum includes bonuses which are very realistic," the Russian businessman said.
"United started to make offers which we declined several times – £21.6m, £28.8m, £36m, even £50.4m with bonuses.
"Right now English football is on a different financial level and if United decides to buy somebody it's hard to stop them."