Just a week before making her Broadway debut as Roxie Hart in Chicago, Rumer Willis got her feet wet with a sultry performance last night during Jim Caruso's weekly Cast Party open-mic show at Birdland. Willis, who will star in the long-running musical September 14-November 1, took to the stage alongside musical director Billy Stritch to perform the legendary torch song "Fever," and it sure did deliver on what the lyrics promise. Check it out below.

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