Chelsea remain interested in Sandro and had a £65 million bid rejected last summer, but Juve may now be tempted to sell as the Brazilian has struggled for his best form this season.
United will also allow Matteo Darmian to leave to free up space in the squad for Sandro, and Turkish side Galatasaray have expressed an interest in the Italian.
The Red Devils have issues at left-back with former winger Ashley Young having been moved to full-back this season and impressed in the role.
Young's form has seen him recalled to the England squad, and he has also scored his first two goals in 19 months during November's win over Watford, per WhoScored.com:
The Englishman turns 33 next year and is clearly not a long-term option at left-back for United, although the club do still have Luke Shaw.
The 22-year-old made his first Premier League start of the season against Bournemouth on Wednesday and did enough to impress football writer Liam Canning:
However, Shaw still seems to be a long way off convincing Mourinho that he deserves a regular place, so it would be little surprise if the club did look to strengthen at full-back.
United could also offer Bordeaux £30 million for Malcom, with the club still keen to bring in a winger, per Jordan Seward for MailOnline.
The club scouted Malcom last summer and may make a move in January, although Bordeaux could be "unwilling to negotiate until the summer."
The 20-year-old has been in fine form this season with seven goals and four assists in 17 Ligue 1 appearances.
WhoScored.com show how Malcom's attacking statistics compare favourably with Kylian Mbappe and Leroy Sane:
Mourinho wanted to bring in Inter Milan winger Ivan Perisic last summer and could still try and sign him in January, even though he has since signed a new deal with the Serie A side, per Mike McGrath at The Sun.
The United boss does appear to want to bring in another wide player, which would give United more attacking options and also provide more service to striker Romelu Lukaku.