Ted Ligety became the first man in 45 years to earn three gold medals at the world championships, winning the giant slalom in dominating style on Friday.
The American can match French great Jean-Claude Killy, who earned four golds in 1968, if he's first in the slalom on Sunday.
"I am super-pumped. This is such a cool feeling," Ligety said. "I am glad I've done it."
Defending champion Ligety, who also took the super-G and super-combined titles, built on his big first-run lead to finish in a combined time of 2 minutes, 28.92 seconds.
Marcel Hirscher of Austria was 0.81 behind in second, and Manfred Moelgg of Italy was third, trailing Ligety by 1.75.
Ligety is the first American to win two world GS titles and equaled Bode Miller's American record of four gold medals at the worlds.
After sunshine in the morning, grey clouds moved in and worsened visibility for the final run. In front of about 35,000 spectators, Ligety increased his 1.31-second advantage over Hirscher from the first run to 1.68 before slowing down to avoid risks.
"I wasn't easy. I took some risks, but it was very difficult," Ligety said. "It was pretty dark and bumpy. I had several mistakes, but I could afford them being 1.3 ahead."
Hirscher, the defending overall World Cup champion, posted the fastest time in the final run to win his second medal of the worlds after taking gold in the team event.
Hirscher hurt his lower back while GS training in nearby Haus on Thursday and had more treatment after his first run.
"Normally you would stay in bed," Hirscher said. "I had only had four or five hours of sleep. My neck also hurts ... it was difficult with the expectations. It was difficult to race and I am extremely happy with silver."
Ligety positioned himself for the victory with another stunning display of GS skiing in the first run. The American has dominated the discipline this season by winning four of five World Cup races, mostly with huge time differences.
"I felt like I skied pretty well," Ligety said. "I skied clean the whole way and I was pushing hard and I think other guys maybe didn't ski as well as they normally do. But I felt like I had a solid run."
Aksel Lund Svindal of Norway was second after the opening run but had only the 13th fastest time in the final run. He lost third place to Moelgg by 0.04.
"Ted is the man," Svindal said between runs. "He's the best in the world. ... It's not possible to beat Ted, I think."
Hirscher was regarded as Ligety's closest challenger after beating the American in Val d'Isere, France, in December and coming close to doing so again in Adelboden, Switzerland, last month, where the Austrian led until a mistake before the finish.
Austrian coach Andreas Puelacher placed the gates for the first run, but the course set didn't seem to favor Hirscher, who lost the most time to Ligety in the middle section. He trailed the American by 1.43 at one point before slightly reducing his deficit.
A three-time World Cup GS champion, Ligety won his 15th World Cup GS race in Adelboden on Jan. 12.
"It's tough when we haven't raced this long in giant slalom." Ligety said. "It kind of takes your edge off. I've just had a good feeling on this hill and snow and I have high confidence, so I think that helps me right now."