Hirscher's second run of 56.11 was the best of the day, leaving the reigning overall World Cup champion 0.21 seconds clear of Norway's Henrik Kristoffersen.
Alexander Khoroshilov of Russia, who led after the opening leg, finished third, 0.32 behind the winner but over 0.7 seconds clear of Fritz Dopfer in fourth place.
Alpine skiiing LIVE on Eurosport: TV schedule
Skiing LIVE on Eurosport Player
The most dramatic moment of the day came when Switzerland's Luca Aerni lost control and a gate flew out of the ground.