Manchester United are keen to add the Brazil international to their line-up with Luke Shaw, 22, set to leave the club in the summer having failed to impress Mourinho during the second half of the season.
Previously linked with Tottenham full-back Danny Rose, 27, the Red Devils are thought to be unwilling to match the London club’s asking price which is set a similar level to that which Manchester City paid for Kyle Walker last summer.
Mourinho tried to watch Celtic’s Kieran Tierney during Scotland’s recent friendly with Costa Rica but an injury kept the PFA Scotland Young Player of the Year out of the starting line-up.
With Bournemouth and Liverpool both keen on the 20-year-old, United’s dilemma is whether to get involved in a bidding war for an untested player or wait for Sandro.
Their cause for the 27-year-old is helped by Matteo Darmian’s desire to leave Old Trafford. It was recently claimed in the Italian media that the left-back has given his word to Juventus that he will join the Bianconeri if he leaves United.
That gives United the opportunity to try to negotiate a swap deal for Sandro, although a considerable fee will still be payable for a player who was valued at £62m last summer.