The Austrian led Matts Olsson of Sweden by 0.94 seconds with Marco Odermatt of Switzerland third, 1.00 behind, on the challenging Gran Risa course.
Odermatt's performance with the No. 27 bib showed that the two-time junior world champion in GS is becoming a threat.
Manuel Feller of Austria stood fourth and Hirscher's rival Henrik Kristoffersen was fifth.
American Ted Ligety failed to finish.
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