Miller, who captured a night slalom in Madonna di Campiglio in mid-December, repeated his success on the tough, icy Kuonigsbergli course, winning with a two-run aggregate time of 1 minute, 33.24 seconds. His time was almost two seconds ahead of runnerup Ivica Kostelic of Croatia.
"I knew I was going to have to go all out, the way all the guys were skiing here," said Miller, a native of Franconia, N.H., "In the second run, I pushed really hard and gave it my all."
Kostelic, the winner of the season-opening slalom in Aspen and third-place finisher in Kranjska Gora, Slovenia, crossed in 1:35.16. World championship bronze medalist Mitja Kunc of Slovenia placed third in 1:35.35.
Finn Kalle Palander, who was second at the 1999 world championships in Vail, Colo., dropped from third to fourth with a time of 1:35.55 after an error-filled second run.
Chip Knight was the only other America to finish, crossing 17th in 1:36.30. Erik Schlopy continued to struggle, straddling the first gate pole in the opening leg.
Miller has finished six times in the top-10 this season. His victory boosted him into second in the overall World Cup standings behind leader Stephan Eberharter of Austria.
Eberharter leads with 732 points, well ahead of Miller's total of 540. Switzerland's Didier Cuche, who won Saturday's giant slalom, sits third on 497.
Miller also sits second behind Kostelic in the discipline standings. Kostelic leads with 311 points, while Miller has amassed 280. Austria's Mario Matt is third with 267.
The 24-year-old Miller won a night slalom in Madonna to become the first American to win in the discipline since Steve Mahre in 1983. That victory came just two days after Miller clinched a giant slalom in Val d'Isere, France, to replace Mahre's brother, Phil, in the U.S. ski history books. Miller also became the first American to win at the Swiss resort.
Though this was only the second World Cup slalom ever staged at the scenic Swiss station, no American ever has won in the giant slalom staged here since the World Cup's inauguration in 1967. His results this season have made him a strong contender for the technical events for the games in Salt Lake City in February.
Only three slalom races remain before the Olympics. The men's technical specialists will move to Wengen for a slalom and a combined event in which skiers race in both a downhill and slalom.
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