Manchester City will be due a windfall should Manchester United sign either Jadon Sancho or Rabbi Matondo this summer.
The Manchester Evening News says a sell-on clause of 15 per cent on top of the £8m fee was negotiated with Dortmund when Sancho left the Etihad in 2017, meaning for example that a £100m transfer fee would give the Blues £13.8m.
United are looking at Schalke winger Matondo as a cheaper alternative to Sancho in a market that has been made more uncertain by the financial impact on the game from Covid-19.
Schalke are said to be looking to sell first-team players, which could help United strike a bargain deal.
Thanks to the terms agreed when Matondo departed City's academy, the Blues will get 10 per cent of any fee paid by Matondo's next club.