Looking good, Kelly!

Kelly Clarkson has definitely been slimming down in preparation for the debut of her new NBC singing competition Duets -- and showed off the impressive results at the Billboard Music Awards in Las Vegas Sunday night.

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The inaugural American Idol winner and "Stronger" singer, 30, wore a daring red gown with a seriously plunging neckline and cutouts in the side, all showcasing a newly taut, skinnier figure.

Crooning her new single "Darkside" live for the first time, Clarkson kept her makeup look fairly simple, and wore her wavy brown locks down to her shoulders.

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Clarkson, whose weight has fluctuated up and down since her days on American Idol, will be hitting the small screen again this week when her new ABC singing competition Duet debuts later this week with Robin Thicke, Jennifer Nettles and John Legend.

Back in March, Us Weekly broke news that Clarkson had a new man in her life: Brandon Blackstock, the son of Clarkson's own manager, Narvel Blackstock (and stepson of Reba McEntire).

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"Before Brandon, Kelly had a really tough time with love," an insider says of the Grammy winner, who split from singer Graham Colton six years ago. "[Brandon] is just what she needed."

This article originally appeared on Usmagazine.com: Kelly Clarkson Shows Off Slimmed-Down Bod at Billboard Music Awards