"You can't do anything at the moment. He's way ahead," former overall winner Ivica Kostelic said of Ligety. "You need a lot of work to do something like that, and a lot of talent as well.
"He's skiing on the edge most of the time, and his angles are bigger than everybody else," added Kostelic, who finished 21st, more than six seconds back. "With the way my knees are I can't do that."
Both Hirscher and Kostelic acknowledged that they have been studying video of Ligety. The highlight in this race was Ligety's first run, when he posted a massive 2.40-second advantage over Hirscher.
Steven Nyman, another American, won the downhill in nearby Val Gardena on Saturday.
Women's giant slalom
In Courchevel, France, Tina Maze of Slovenia won her fourth straight World Cup giant slalom race to extend her overall lead at the top of the standings as defending champion Lindsey Vonn lost her balance in the first run and failed to finish.
The 29-year-old Maze had a comfortable lead of 0.63 seconds over Frenchwoman Tessa Worley after her first run and then held off Austria's Kathrin Zettel in the second to win by 0.22. Worley was third, 0.40 back.
The race was held despite heavy snowfall and the Stade Emile-Allais course was hard and bumpy, with poor visibility for the first run.
In La Plagne, France, Beat Hefti of Switzerland won a four-man bobsled race to end a run of four consecutive wins by World Cup titleholder Alexander Zubkov of Russia.
Pushed by Alex Baumann, Thomas Lamparter and Juerg Egger, he beat Zubkov's Russia 1 crew of Alexey Negodaylo, Dmitry Trunenkov and Maxim Mokrousov by .09 seconds.
World and Olympic champion Steven Holcomb's USA 1 crew finished a disappointing seventh .74 behind Hefti, who is 10th in the overall standings.
In Harbin, China, Samuel Schwarz of Germany beat Shani Davis of the U.S. to win the 1,000-meter World Cup speedskating race in China to rise to second in the overall standings. Schwarz finished in 1 minute, 9.69 seconds 0.18 ahead of Davis and 0.23 in front of Hein Otterspeer of the Netherlands. American Denny Morrison leads the standings after five races with 325 points, 11 more than Schwarz. Otterspeer is third with 310.