Paramedics spent 40 minutes trying to revive Boban after he collapsed on the field just moments after being hit in the chest by the ball.
At first, the match went on as Boban appeared to be fine before dropping to the ground and completely losing consciousness according to HRT Sport.
Despite the medics' best efforts, he was pronounced dead on the spot moments later. The cause of death is yet to be announced.
Earlier this month, the football world mourned another loss, when Fiorentina captain Davide Astori passed away in his hotel.