Manchester United are reportedly willing to pay £45m to sign Fabinho from Monaco and are confident of getting a deal over the line.
Versatile Brazil international Fabinho, who can cover at both right-back and defensive midfield, is said to be among Mourinho's top targets ahead of next season.
United had been tipped to make a move for the 24-year-old last month, but instead focused solely on bringing Sanchez to the club from top-flight rivals Arsenal.
According to respected Italian journalist Gianluca Di Marzio, however, United will now go all out to land Fabinho for what they feel is a bargain price.
There are suggestions that discussions are already at an early stage between the two clubs, but other interested parties - Paris Saint-Germain among them - are expected to make themselves known.