Milan chief executive Adriano Galliani is hoping Ronaldo has not played his last game for the club.
Ronaldo suffered a knee injury against Livorno on Wednesday, minutes after coming on as a substitute, and he has been ruled out for nine months.
With his Milan contract expiring in the summer, his chances of earning an extension appeared to hinge on the Brazilian proving his fitness.
But while Galliani did not guarantee the powerful striker a new deal, he outlined his wish to see Ronaldo in a Milan shirt again.
Sad image
"We hope this very sad image on Wednesday is not the last we see of him on the field," Galliani told Gazzetta dello Sport.
"Ronaldo is still not 32 and even if I don't comment because I am not a doctor, I hope he returns to play and that he does so in our jersey.
"Ronaldo is perhaps the best player Brazil have had since Pele."
Milan coach Carlo Ancelotti is optimistic that the latest setback will not signal the end of the injury-troubled forward's career.
Ancelotti said: "Now everything is in his hands. I am convinced Ronaldo will return to playing because football is his world and we will wait for him.
"The first time he had this type of injury, to the left knee, he recovered perfectly. I don't see why he shouldn't manage this time."