Kilmarnock's Scottish Premier League match with Hibernian at Rugby Park was abandoned after a supporter required medical treatment on the pitch side.
A Police Scotland spokesman later said the man had died in hospital.
The spectator collapsed at the start of the second half with a suspected heart attack, and referee Kevin Clancy stopped the game, with the score 1-1.
Medical staff attended the scene before the supporter was taken to hospital by ambulance and the game abandoned.
A statement from Kilmarnock chairman Michael Johnston read: "The length of time the players were off the park was a problem but the overriding factor was respect for the fan and his family.
"He collapsed and was tended to by medical staff of both clubs and was taken to Crosshouse Hospital by ambulance.
"The referee, in consultation with SPL delegate Frank Coulston and the match commander at Rugby Park, decided to abandon the game."
Hibs had taken the lead through a deft finish from Alex Harris after 21 minutes played in the match, but Kilmarnock responded with a Kris Boyd volley 10 minutes later.