The founder of the supporters club of the Belgian national team died of a heart attack after the country's crushing 4-0 victory over Hungary at Euro 2016 on Sunday, the national football association said on its website.
Erik Reynaerts, 50, had been in Toulouse where Belgium was playing Hungary in the last 16 and suffered a cardiac arrest after the match, the football association said. He died on Monday.
"Our thoughts go out to the family and friends of Erik and we will always carry him with us," the Belgian FA said on its website.
Reynaerts had set up the official supporters club of the Belgian Red Devils, as the national soccer team is known, in 2012 and named it "1895" after the year in which the Belgian FA was founded.
Belgium will face Wales in the quarter-finals on Friday.