Ronaldo underwent surgery in Paris on Thursday after rupturing tendons in his left knee during Wednesday's 1-1 draw against Livorno and is expected to be sidelined for up to a year.

The 31-year-old's contract at the Rossoneri ends on June 30 but solicitor Fabiano Farah is confident Ronaldo will still be a Milan player when he comes back from injury.

"Everything makes us think that the club are interested in renewing his contract," Farah told Brazilian daily Terra.

"Vice-president (Adriano) Galliani has already expressed this desire.

"Ronaldo wants to return to playing, but his primary aim is to get better and have a good rehabilitation.

"He is the type of person that continues right to the end in his challenges, he has always won them.

"He is a born fighter and I am sure he is ready for this new battle."

These are the qualities that Eric Rolland, the surgeon who operated on Ronaldo, knows will be vital if the World Cup winner is to play professional football again.

"He will need a lot of energy to return to playing," Rolland told French daily Le Parisien.

"And his motivation will be the determining factor.

"The rehabilitation time will be very long because his injury involved a tendon and not a ligament.

"We have to give him back some solidity.

"We know at once therefore that Ronaldo will not be able to run for at least six months and that he will not be in reasonable condition to train before nine months."