The big-spending Serie A outfit have endured a disappointing start to the season so far, sitting seventh in the table having lost five of their opening 12 league games.
Manager Vincenzo Montella is understood to be close to the sack at San Siro, but that has not prevented Milan from planning their January transfer activity.
Calciomercato claims that they have identified Willian as a possible target when the window reopens, with Chelsea also considering offloading the Brazilian forward.
Willian has started just six matches in the Premier League so far this season and is reportedly deemed to be dispensable by the English champions, with Chelsea looking to raise funds for Paris Saint-Germain winger Lucas Moura.
A number of Chinese Super League clubs have also been credited with an interest in the 29-year-old, who joined Chelsea from Anzhi Makhachkala in 2013.