After the transfer to Bastia fell through, Popović then joined Osijek where he played in only eleven matches before his death in a road accident in the evening of 23 October 2002.
Although some believed he was putting too much pressure on the young player, his decision paid off after Popović scored eleven goals in 14 appearances during the second part of 2000–01 Druga HNL season.
In the first part of the 2001–02 Druga HNL season Popović scored 22 goals in 15 appearances, which brought him the top scorer title even though he did not play a single game in the spring.
[2][3][4] Popović won two caps for Croatia under-21 team, making his debut on 7 May 2002 in a friendly match against Hungary in Zaprešić, and scoring the second goal in a 2–0 victory.
Popović, who was rushing to his childhood home to watch a Champions League match, lost control over his Golf at high speed and the vehicle hit a light pole.