Former Brazil striker, Ronaldo has revealed he could choose to retire rather than prolong his career after fighting back from a serious knee injury.

The 32-year-old spent nine months on the sidelines after rupturing a tendon in his left knee while playing for AC Milan in February but returned to action earlier this week, playing 22 minutes of an exhibition match.

Ronaldo’s contract with Milan expired in the summer and he has been training with Brazilian outfit Flamengo in an effort to return to full fitness.

The three-time world player of the year has voiced his desire to resuscitate his career at either Flamengo or Manchester City - and turned down an offer to join Italian side Siena earlier this month - but admits doubts remain over making a comeback.

"I don’t know if I will continue to play or if I will retire," Ronaldo said. "I have not taken a decision yet.

"I am in no hurry to make a decision. I want to complete my recovery.

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

The former Barcelona, Real Madrid and Inter Milan striker added that while he was happy to return to action in the charity game in Morocco on Monday, he is under no illusions as to how much work still needs to be done.

"It was beautiful to return to play because football is my life," he said. "But it was just an exhibition as I only played for 22 minutes.

"Professional football is a different issue."