Born in Zagreb, Ivančević took up gymnastics at an early age but switched to athletics at the age of 15 after ten years of little success in her previous sport. Focusing on hurdling instead, she competed internationally as a youth and ran in the heats of both the 2001 World Youth and the 2002 World Junior Championships in Athletics. She ran a Croatian junior record at the latter event. She gradually improved her personal bests in her first seasons as a senior athlete, having a best of 13.86 seconds for the 100 m hurdles in 2003, 13.64 in 2004, then 13.60 in 2005. She competed in the heats only of the 2005 European Athletics U23 Championships and made her senior debut at the 2006 European Athletics Championships, again only competing in the heats. A personal best of 13.42 seconds came in 2006, but a further appearance at the 2007 Summer Universiade saw her again fail to pass the heats.