Lady Gaga was the celebrity mentor last night on "American Idol" -- and she used her time with rocker James Durbin to show him how to really shake those hips.

Durbin tackled "Love Potion #9" for his Leiber & Stoller selection, but Gaga wasn't feeling his performance in rehearsals -- so she stood up, told him he needed to loosen up a bit and started literally moving his hips for him.

He didn't really take Gaga's advice when it came time for his live performance, but the judges still ate it up -- with Randy Jackson telling him "You're having a moment every single week."

Check out his performance above -- do you think James is the one to beat for the crown this season?

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