BILD says United are leading the race for the Chilean's signature.
Vidal's future in Bavaria is under threat following the capture of Leon Goretzka from Schalke.
And Allianz Arena chiefs could now cash in as they look to reshape the squad with younger faces.
It's believed that Jose Mourinho is keen on swooping for Vidal, who was strongly linked with an Old Trafford switch during the Louis van Gaal era. Mourinho sees Vidal as a successor for Michael Carrick.