Sao Paulo: Three-time football player of the year Ronaldo was expected to end his career on Monday, Brazilian media reported.
The 34-year-old striker for Sao Paulo's Corinthians was to announce the move at a press conference, the Estado de Sao Paulo newspaper reported online.
"I would like to continue, but I can't. I can no longer bear it. It is time. But it has been wonderful," he was quoted as saying.
His contract runs until 2011, but Ronaldo has been criticized by fans after the Corinthians fell out of the Copa Libertadores, South America's largest football tournament, in the first round.