Schalke winger Rabbi Matondo's contract carries a buyout clause.
Welsh winger Matondo included a clause in his deal to move to FC Schalke last January which would see him allowed to move to any English side if they matched the fee.
However, former club Manchester City would have a potential advantage in any deal for the 19-year-old with their own buyback clause which could see Matondo rejoin them for €46.5 million.
United are monitoring Matondo as a possible back-up target for Borussia Dortmund star Jadon Sancho this summer, with the Wales international viewed as a more cost-efficient option.
Despite the aforementioned fee United's initial interest comes from the belief they can sign him for much lower than his release clause, viewing him in the same 'low-risk buy' bracket to Daniel James, who joined for £15million from Swansea City last summer.