AC Milan medical chief Jean-Pierre Meeserman is confident Ronaldo will play again after his knee injury suffered on Sunday.
Pietro Volpi - Inter Milan's doctor between 1995 and 2000 - thinks it is premature to bid farewell to Ronaldo.
"It is a very serious injury, but it can be repaired and technology has made huge steps in recent times," he told Sky Tg24.
"A recovery will probably take between eight and 10 months, but I wouldn't be so pessimistic about Ronaldo's future.
"The real problem is that he is eight years older than he was in 2000 and that makes it harder to get to peak condition in sport."