The Italian giants had signed a deal to keep Bakayoko on loan for the entire season.
But there is speculation that he will be asked to return to Chelsea in January.
According to Corriere dello Sport, Bakayoko has been given six games to prove his worth by the Italian giants.
Milan are unhappy with his performances, with manager Gennaro Gattuso unimpressed with the player's skill set.
"Bakayoko has to learn how to get the ball," Gattuso said of the Chelsea loanee recently.
"We must work correctly. It will not be easy.
"One week is not enough to remove the defects of a player. I would have preferred to be managing older, more experienced club players."