The start to the 2003 athletics season was promising – Vlašić set a new personal best in Linz with a jump of 1.98 m and finished fourth at the World Indoor Championships ten days later, her highest finish in a major world tournament. June and July yielded further progress, jumping 1.98 m again and improving to 1.99 m to win her first IAAF Golden League event at the Gaz de France. Days later, she jumped the two metres height for the first time on home soil at the IAAF Grand Prix Zagreb. Although Hestrie Cloete won the competition overall, Vlašić's defeat of the psychological barrier and improved personal best was the highlight of the meeting and Cloete praised the young athlete's performance. Vlašić took gold at the 2003 European Athletics Under-23 Championships, and then she improved her best by another centimetre at the Zürich Grand Prix which qualified her for the World Championships and the first IAAF World Athletics Final. Despite such previous highs, her season ended on a low note as she failed to win a medal at either the World Championships (finishing seventh with 1.95 m) or the Athletics Final in Paris (ending up fourth with 1.96 m). Although she had failed to reach the podium at the major championships, only three athletes managed to jump higher than her personal and season's best of 2.01 m in 2003.