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Partners in crime? Not anymore!

Giuliana Rancic and Kelly Osbourne were once thick as thieves as they co-hosted "Fashion Police," but now it seems they want nothing to do with each other.

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An insider told Us Weekly that "Kelly is dead to Giuliana."

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The reason for the tension: Giuliana feels that Kelly didn't have her back when she was embroiled in controversy following her on-air joke about young actress Zendaya Coleman's hairstyle at the Oscars.

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Shortly after the joke — and after many in Hollywood fiercely backed Zendaya -- Kelly tweeted her feelings on Twitter, saying that she doesn't condone racism and that she was thinking about leaving the show, which she did shortly after. Just a week ago she even called Giuliana's behavior "heartbreaking."

Giuliana, the source said, feels like Kelly "threw her under the bus."