EMF headliner Mary J. Blige performed "Why" and mentored the show's contestants.
EMF headliner Mary J. Blige rocked American Idol last night with a hot performance of her latest single, "Why?" off My Life II... The Journey Continues.
Not only did the soul singer show the contestants how to command the stage, but she also acted as the week's mentor, helping contestants take their vocal skills to new heights.
See what she'll be bringing to the main stage come this Independence Day weekend in New Orleans.