Christina Aguilera is often touted as the teeny-popper with a difference: She can actually sing. But headlining Z104's holiday bash at Nation Sunday night, the former Mickey Mouse Clubber didn't perform any amazing vocal feats in a frustratingly brief appearance.

Following the bright girl-bop of Vitamin C and the boy beats of LFO (Lyte Funky Ones), Aguilera took the stage. Augmented by three male dancers (who occasionally did the same steps), she launched into "Come On Over (All I Want Is You)" but struggled with her headset microphone for much of the number.

Set to recorded backing tracks, her new single "What a Girl Wants" was much better, featuring the whomping beats and spiraling, breathy vocal formula that Britney Spears has found so lucrative. Next was what she called a "dancey" version of her holiday single, that ol' roasting chestnut "The Christmas Song." Hopefully the late Mel Torme is in a better place where he won't have to hear Aguilera trash his holiday standard.

A week shy of her 19th birthday, the singer strutted suggestively around the stage like someone far older, but had no trouble trilling the girlish lead of "Genie in a Bottle," which closed the 20-minute set. The crowd (many middle-schoolers with parents in tow) reacted well enough, though it was hard not to feel cheated that Aguilera didn't treat her fans to at least a few more songs.

CAPTION: Christina Aguilera: Whomping beats and breathy vocals.