Schalke chief Christian Heidel is backing Leroy Sane's Manchester City for big success this season.
Schalke sold Sane to City 18 months ago for €50m - plus extras due in winning bonuses.
BILD says S04 will be due €1m should City win the Premier League title and €500,000 if they reach the Champions League final.
Should City win the European title, another €500,000 will be due.
"Yes, I don't think Man City will have to pay us much more after this season," smiled Heidel when reflecting on Sane's success.
