Novak Djokovic's winning streak was finally halted by injury in Umag, allowing Stanislas Wawrinka to claim his first ATP title.
The rising Serb star threw in the towel during the first-set tie-break due to respiratory problems.
Djokovic, who was on a nine-match winning run coming into Sunday's final, was trailing 3-1 in the breaker at the time.
That allowed his Swiss opponent to win the Croatia Open - his first victory at the highest level.