Ryan Seacrest has revealed that American Idol has a very special guest mentor next week. 

Tweeting to his 4.4 million followers today, May 6, he exclaimed that the 'Judas' hitmaker will be lending her professional and musical talents to the finalists:

"I only have one word for our mentor on @AmericanIdol next week.......... Gaga."

This news comes on the same day that Billboard unveiled Gaga's Monster Ball tour as the biggest tour ever by a debut headlining artist. Watch American Idol finalist Haley Reinhart cover the pop icon's 'You and I' here: