The Holland international defender has rejected a new contract offer from United and is ready to leave Old Trafford in 2021.
Fussball Transfers says a move to Germany could now be on for Fosu-Mensah.
In England, Hertha Berlin have been mentioned, but aren't alone. Borussia Mönchengladbach and Hoffenheim are also watching developments.
Across all competitions, the Dutchman has only played 108 minutes this season.