Rafael is set to end his seven-year stay in Manchester this summer, according to Sky Sports.
The Brazilian full-back failed to impress Louis van Gaal last season, making just 11 appearances for the Red Devils.
Fiorentina and Napoli are both tracking Rafael, with Turkish giants Galatasaray also understood to be interested.
Rafael's twin brother Fabio, who moved to United alongside his sibling in 2008, left Old Trafford for Cardiff City in January last year.