"RIP Sinisa," the club said on Twitter, posting a photo of Mihajlovic. He managed the club's main team from 2010-2011.
In the summer of 2019, Mihajlovic announced that he had leukemia. Throughout the season, he periodically underwent treatment for cancer, while continuing to manage the team. The coach underwent three courses of chemotherapy and a bone marrow transplant. In March 2022, he announced that the disease had returned and he needed to undergo a new course of therapy.
Over the course of his career, Mihajlovic played for Italian football clubs Roma, Sampdoria, Lazio and Inter and then managed Bologna, Catania, Fiorentina, Milan and Torino, as well as Portugal's Sporting and the Serbian national team.
He is survived by his wife, their five children and a granddaughter.