AIK keeper Ivan Turina has died in his sleep of a suspected heart failure, at the age of 32.
Turina had made 89 appearances for the Swedish club after joining them in 2010 from Dinamo Zagreb.
The club said in a statement: "It's with great sadness and shock that AIK Football can confirm that goalkeeper Ivan Turina died overnight between Wednesday and Thursday.
"Ivan died suddenly in his sleep and there are no suspicions of a crime at this point in time."
AIK chairman Johan Segui admitted that the club were aware the keeper had heart problems before he signed. He told newspaper Expressen: "We knew that he had a congenital heart problem but he was completely healthy."
Supporters have made a temporary shrine at the club's ground in memory of Turina, who is survived by a wife and one-year-old twins.