Rio de Janeiro: Former World Cup and Ballon d'Or winner Rivaldo was admitted to hospital with a bacterial infection, two months after undergoing surgery on his knee, a media report said.
The 43-year-old posted a social media message on Monday, saying he was receiving treatment in a Sao Paulo hospital, Xinhua reported.
"After twice having surgery, I now have a bacterial infection in the same knee where the surgery was made," the former Barcelona forward said.
"I'll be in hospital for a few days to get some antibiotics in the vein," he added.
Rivaldo retired from football in March 2014 but returned in June this year in an attempt to help Mogi Mirim escape relegation from Brazil's Serie B.
But he retired just weeks into his comeback and left his post as Mogi Mirim president after falling out with club officials.
Rivaldo won the Ballon d'Or, awarded to the world's best player, in 1999 and was part of Brazil's 2002 World Cup-winning team.