Veteran Olympic official John Coates stood down early Monday as head of sport's highest court after being treated for cancer.
"Mr Coates indicated that, after completing six months of chemotherapy treatment for cancer, his current health did not allow for international travel," the Court of Arbitration for Sport said in a statement.
The 75-year-old Australian lawyer was an influential vice president of the International Olympic Committee, and close ally of its then-president Thomas Bach, until his membership expired last year.
Coates joined the IOC in 2001 one year after overseeing the bidding and organizing committees for the Sydney Olympics. His status at the IOC was key to Brisbane being fast-tracked as host of the 2032 Summer Games.
He was a member of the sports court's management board, known as ICAS, when he was first elected its president in 2010.
CAS said the board's senior vice president Michael Lenard, who competed for the United States in handball at the 1984 Los Angeles Olympics, will step up as its interim leader. The next election is due in May 2027.