Pop star Rihanna bailed on her private Palm Beach concert Saturday and organizers quickly tapped Jennifer Hudson to step up to the plate, RadarOnline.com has learned.

Rihanna was scheduled to perform Saturday at the grand ballroom in Donald Trump's Mar-a-Lago Club, and sing for people who dropped more than $200,000 to see her, according to Page2Live.com which broke the story.

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The website reports that the singer's doctor barred the Grammy winner from flying because of acute bronchitis. The performance was part of a fundraiser for the Dana-Farber Cancer Institute.

On Friday, Rihanna stepped out to promote the launch of her new fragrance Reb'l Fleur at the Macy's department store at Lakewood Mall in Lakewood, California.

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Perhaps Rihanna is just taking a day to relax before her big performance Sunday at the 2011 NBA All-Star game at Staples Center in Los Angeles. According to NBA.com she's scheduled to perform live during halftime.

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