United are in the market for a new left-back having seen Ashley Young fill in in that position for the majority of the season so far, with manager Jose Mourinho still unconvinced by the likes of Luke Shaw, Marcos Rojo, Matteo Darmian and Daley Blind.
Sandro is understood to be top of Mourinho's wish list in January, and Juventus are now thought to be open to offers for the Brazil international after being unimpressed by his form this season.
Chelsea saw a £65m offer for the defender turned down during the summer and are expected to revive their interest once the transfer window reopens next month, but The Mirror reports that they will face competition for his signature from United.
The Red Devils have also been linked with Tottenham Hotspur's Danny Rose, but Sandro is understood to be their primary target and they have now been given the go ahead to launch a £60m bid in January.
United's local rivals Man City have also previously been linked with a move for Sandro, who has scored one goal and registered three assists in 10 Serie A appearances for Juve this season.