Former Brazil, Chelsea, Paris Saint-Germain and AC Milan defender Alex has announced his retirement because of a serious knee injury.
Alex, 34, will need further surgery and said the pain caused by the problem had become "unbearable."
He told GloboEsporte that he had made the decision to end his playing days after talking to members of his family.
Alex has been without a club since leaving Milan in the summer and had been linked with Santos and Porto.
"After speaking with my family, I have decided to retire," he said. "The pain is unbearable and the injury has got worse."
Tests revealed that no cartilage remained in part of his right knee.