Bacca has been at the San Siro for two seasons, scoring 34 goals from 76 appearances in all competitions, but his days at the club may now be numbered.
The Rossoneri appear to be waking from their slumber and have spent big over the summer, with the capture of attacking players Andre Silva, Fabio Borini and Hakan Calhanoglu.
It all means that the Colombia international could be on his way out and, it is thought he favours a return to Sevilla where he scored goals for fun before joining Milan.
However, Ligue 1 champions Monaco have now thrown their hat into the ring for the South American, whose agent confirmed that the principality club are keen.
"Monaco called me to ask for information about the player's situation," Sergio Barila told Caracol Radio. "He has already been at Sevilla and knows La Liga well so there is a chance.
"If he does leave Milan and if Sevilla offers an important possibility, I think it will be evaluated in a calm manner."