Thiago Silva feels Milan would lose an "outstanding player" if Ronaldinho were to leave once the January transfer window opens.
Antonio Cassano's arrival at San Siro appears to have brought the curtain down on Ronaldinho's time with the Rossoneri.
Former club Gremio claim to have reached personal terms with the player and his exit now appears inevitable.
Speaking to Sky Sport Italia as Milan arrived in Dubai for a winter training camp, Thiago Silva said: "If Ronaldinho leaves we will lose a lot because he is an outstanding player.
"We didn't talk about it on the plane. Ronaldinho and I slept [on the flight] from Sao Paulo to Dubai."
Thiago Silva also gave his reaction to Leonardo's appointment at Inter.
"This story arrived in Brazil. I am sorry because he did many positive things for Milan and now he is going to Inter. But Leonardo is a good lad, also off the pitch.
"In my opinion, he'll do a great job even there."
Asked if Leonardo had made the right decision, Thiago Silva said: "For him, yes."
Betting on Serie A? Bet365 are offering a 100% deposit bonus, up to £200 - find out more