It was Svindal's third win of the season after a pair of downhill victories last month, after he beat the tour's Super G leader Jansrud by half a second with the finish line moved uphill to preserve the course for Saturday's downhill.
Austria's Matthias Mayer finished third just 0.01 of a second ahead of fourth-placed compatriot Hannes Reichelt, who fell further behind Jansrud in the overall Super G standings as did Austrian Vincent Kriechmayr after finishing 10th.
The race was delayed by 90 minutes due to heavy snowfall and Jansrud must have thought he clinched it after grabbing pole position and seeing Svindal trail in the upper half of the steep and narrow course.
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But the 35-year old former Olympic champion, who won three medals including the Super G gold at the 2010 games in Vancouver but failed to finish on the podium in any event four years ago in Sochi, steamrolled through the lower section.
Svindal will have a shot at completing the double on Saturday as he tops the downhill standings and will start as the favourite to win at the famous Hahnenkamm course.