After sitting at the judges table all season long, Mariah Carey stepped onto the "American Idol" stage in last night's finale and delivered a medley of her biggest hits shortly after Candice Glover was crowned the next "Idol."

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While Carey's fans came out in droves to lavish praise on the singer's highly anticipated performance, some on Twitter wondered if the megastar was lip-synching her performance.

Mariah's rep quickly defended the superstar, telling ET she absolutely sang the entire medley -- "Vision of Love," "Make It Happen," "My All, Hero," "We Belong Together" and her new single "#Beautiful" -- completely live.

The rep added that Carey delighted the crowd in between live shots by singing additional hits.

Mariah wasn't the only familiar face to take the stage as former judge Jennifer Lopez returned to perform her new single "Live It Up" along with Pitbull.

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The "American Idol" finale also included performances by "Gangnam Style" singer Psy, season 8 runner-up Adam Lambert and panel judges Keith Urban and Randy Jackson ...to name a few.