Darmian is an Italian international, but has struggled since joinind the 'Red Devils' from Torino, and the 'Old Lady' have put together a deal worth around €12million.
Jose Mourinho's side are already in the market for a replacement, with talks reportedly ongoing with Sime Vrsaljko, Joao Cancelo and Djibril Sidibe to fill the Darmian sized hole in the defence.
The move would add to what has already been a busy few days at Old Trafford, as they move closer to the signing of Fred from Shakhtar, although Manchester City could scupper those chances.
Juventus meanwhile face a big rebuild over the summer, with many of their high profile stars leaving the club.