Brazil ace Ronaldo could retire

Ronaldo ruptured a tendon in his left knee in February

Former Brazil striker Ronaldo admits he could retire rather than prolong his career after fighting back from another serious knee injury.

The 32-year-old, who left AC Milan last June, made his comeback in a charity match in Morocco earlier this week.

"I don't know if I will continue to play or if I will retire," he told Gazzetta dello Sport.

"I have not taken a decision yet. I am in no hurry to make a decision. I want to complete my recovery."

The three-time world player of the year had spent nine months on the sidelines after rupturing a tendon in his left knee while playing for AC Milan in February.

Ronaldo will go down in football history as one of the world's greatest-ever players AC Milan's technical director Leonardo

His contract with Milan expired on 30 June and he has been training with Brazilian outfit Flamengo in an effort to return to full fitness.

The former Barcelona, Real Madrid and Inter Milan striker turned down an offer to join Italian side Siena earlier this month and admits doubts remain over whether he will make a comeback.

"I could decide tomorrow or in a month's time what to do, but I still don't know," he said.

"It was beautiful to return to play because football is my life but it was just an exhibition as I only played for 22 minutes. Professional football is a different issue."

AC Milan's technical director Leonardo told BBC Sport that Ronaldo would "go down in football history as one of the world's greatest-ever players".

The Brazilian said he had been in regular contact with his compatriot since he left Milan in June.

"We are very good friends and Milan also still have a very good relationship with Ronaldo," Leonardo added.

"At the moment, he is deciding everything. He has to complete the treatment and get fit - then he can make a decision."