Seeking his fourth win of the season, Hirscher clocked 1 minute, 0.25 seconds down the Stelvio course. Neureuther finished 0.01 seconds behind and Mattias Hargin of Sweden was third, 0.13 behind.
The first run was held at twilight, with the second to be raced under the lights.
The race was moved from Zagreb due to a lack of snow in Croatia.
The course was about five seconds longer than most slaloms, and Hirscher gained a huge chunk of time on the last gates of a steep finishing pitch.