Bailly is one of three defenders who United will allow to leave this summer with Phil Jones and Axel Tuanzebe also deemed surplus to requirements following the arrival of Lisandro Martinez from Ajax.
The Ivory Coast international has impressed during United’s pre-season tour of Asia and Australia with his first preference thought to be to stay at Old Trafford and fight for his place.
With Roma interested in bringing him to Serie A, the 28-year-old is set for talks with Erik ten Hag and should he feel his game time will be limited, he will welcome the opportunity to discuss a move to the Giallorossi, according to Sky Sports.
Bailly became Mourinho’s first signing following the manager’s arrival at Old Trafford in 2016, arriving from Villarreal and starting 24 Premier League matches in his first season in English football.
He has failed to surpass that number since with injury and struggles for consistency ensuring he has remained a peripheral figure at the club.
Mourinho has already turned to another of his former United signings in Nemanja Matic, who joined Roma after leaving Manchester at the end of his contract in June.
A move to the Italian capital would also see Bailly reunited with Chris Smalling, who has rebuilt his career in Serie A having left United in 2019.
Roma are thought to be interested in signing Bailly on loan despite recent reports suggesting he could be available on a permanent deal worth £10m.
The arrival of Martinez at Old Trafford in a £54m deal from Ajax pushes him further down the pecking order.
The Argentina international is expected to fight for a first-team role alongside club captain Harry Maguire, Victor Lindelof and Raphael Varane heading into the new season.
United are still hoping to make further additions to the squad with Christian Eriksen and Tyrell Malacia also arriving in recent weeks.
The club remain locked in talks to sign Frenkie de Jong from Barcelona while Ajax star Antony is also said to be on ten Hag’s wish list.
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