Fiorentina have retired the shirt number worn by Davide Astori, the Italian defender who died on Sunday at the age of 31.
Astori's former club Cagliari have also retired the number 13 shirt - which he wore at both teams.
Capped 14 times by Italy, Astori joined Fiorentina from Cagliari in 2016.
An autopsy on Tuesday reportedly showed he died from a cardiac arrest linked to a slowing heart rate, according to a BBC report.
On Monday, prosecutors opened a routine investigation into his death.
Udine chief prosecutor Antonio de Nicolo said he had opened a "culpable homicide" inquiry - a routine move before an autopsy in Italy.
Doctors who carried Tuesday's autopsy out referred to a "cardiac arrest without a visible explanation, in all likelihood due to a bradyarrhythmia (slow heart rate)", according to both Corriere dello Sport and Tuttosport.
Astori's body is scheduled to be taken to Florence on Wednesday before his funeral on Thursday.
"In honour of Davide Astori's memory, Cagliari and Fiorentina have decided to retire the number 13 shirt," a Fiorentina statement read.
Fiorentina were scheduled to play Udinese on Sunday, but all Serie A games were called off.
Astori, who leaves a wife and two-year-old daughter, came through the youth system at AC Milan before joining Cagliari in 2008.
He spent eight years at the club and had loan spells at Roma and Fiorentina before moving permanently to the latter two years ago.
