X Factor judge Britney Spears was so moved by a performance of Kelly Clarkson's "Stronger" that she tweeted the American Idol alum to encourage her to watch it -- and Clarkson did!

Spears reached out following Thursday's bootcamp sing-off between 13-year old Diamond White and 15-year old Dinah Jane Hansen, each of whom delivered Clarkson's empowerment anthem in their own individual styles.

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Spears could hardly contain herself on Twitter, writing to @Kelly_Clarkson, "I hope you're watching girl! 2 beautiful, STRONG ladies singing Stronger!"

Clarkson, who is on tour in Australia, had positive comments for both teens, too. She replied to @britneyspears: "Just saw it on YouTube and Diamond & Dinah did awesome! Such young girls & already so talented! Tell them great job from me!"

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Clarkson is set to release a greatest hits collection on Nov. 19. A new single, "Catch My Breath," ships to radio Oct. 16.

Watch Diamond and Dinah perform "Stronger" below:

Twitter: @micheleamabile