(CNN) Mikaela Shiffrin proved she really is in a league of her own in the slalom, becoming the first skier in history to win four consecutive world titles in the same event.

The American was third after the morning run, 0.15 seconds behind leader Wendy Holdener, but put in a faultless, textbook performance in her second run to finish almost a second ahead of home favorite Anna Swenn Larsson who took silver.

Swiss skier Holdener was last to go and challenge Shiffrin's daunting time, but a costly error inside the opening seconds cost her any hope of a medal.

Following victory, Shiffrin revealed that she had been struggling with illness throughout both runs on Saturday.

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"I think that I maybe have a small infection in my lungs," Shiffrin told Eurosport after her win. "I've never had this before, it's tough to breathe without coughing.

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