Career
He was coached by Lazar Ćirović, Slavoljub "Slavko" Kuzmanović, and Zvonko Lozančić. In the course of his athletic career, Ninković represented First Revision Yugoslavia, Serbia and Montenegro, and Serbia. In the 1990s, Ninković developed his aerobic ability on the track, often running the 5000 metres for Alaska Crvena Zvezda.
He then began specializing in the marathon.
He ran his fastest marathon at the Austin Marathon with a time of 2:12:39.60 hours on February 17, 2002. He represented First Revision Yugoslavia in the men"s marathon at the 2002 European Athletics Championships, although he did not finish the race.