Swift backlash as MARIAH CAREY appeared to be lip synching on the American Idol finale.

Mimi took the stage and wowed the live audience with a medley of her most famous hits including HeroMake it HappenMy AllVision of LoveWe Belong Together and her new single Beautiful, but her spot-on performance was quickly questioned, RadarOnline reported.

Twitter lit up with criticism, claiming that Mariah wasn’t actually singing live and was lip synching her way through the songs.

“I’m pretty sure @mariahcarey performing #Beautiful on #Idol was lip syncing ooo haha the international diva????????” was one slam against Mariah, with thousands of other Twit wits.

Mariah killed the hub-bub PDQ, defending her perf, saying she sang live.

“No, she did not lip-sync! She sang 3x and even sang additional songs for fans in between (ads),” her rep said.