Former FIFA president Joao Havelange, who ran world football's governing body for two decades, is being treated for pneumonia in a Rio de Janeiro hospital.
The Samaritano Hospital said the 100-year-old Brazilian was in a stable condition, but did not elaborate further.
Havelange presided over FIFA from 1974 until 1998, and was credited by many with expanding football into a truly global game.
He was also a long-time member of the International Olympic Committee until resigning in December 2011 amid allegations he had taken a kickback from a FIFA marketing partner.
Following his IOC resignation, he was also forced to resign as FIFA's honorary president.