Herrera joined Manchester United from Athletic Bilbao in 2014 for £28m and has gone on to make 151 appearances for the club, scoring 16 goals.
Originally, Herrera was used as United’s midfield enforcer by Jose Mourinho upon the manager’s arrival in 2016.
However the Spaniard has since fallen behind summer signing Nemanja Matic in the pecking order and has seen his first-team opportunities begin to dwindle.
AC Milan are willing to offer the 28-year-old a get-out by attempting to bring him to the San Siro this summer, and have been sending scouts to monitor his progress at Old Trafford, according to Tuttosport.
Milan are looking to bolster their midfield and provide competition for the likes of Lucas Biglia and Riccardo Montolivo in the centre of their midfield and are aiming to continue their recent splurge after spending over £150m on fresh talent last summer.
Mourinho reportedly doesn’t want to see his fiery midfielder leave but due to his reluctance to drop either Matic or Paul Pogba from his side, he might be forced into relenting and allowing Herrera to quit Old Trafford and play on a more regular basis in Serie A.
Herrera has recently found himself being linked to a match-fixing scandal, which he denies any involvement in, but should the negative press continue to pile up for the Spaniard, a change of scenery might just be what the doctor ordered.
Mourinho is said to be eyeing Monaco’s Fabinho as a replacement for Herrera.
The Brazilian would cost United around £45m.
Arturo Vidal is also said to be on the manager’s radar, although Bayern Munich are seeking £50m for their Chile international.