AMERICAN IDOL: R&B superstar Usher is the guest mentor on AMERICAN IDOL airing Tuesday, March 30 (8:00-10:00 PM ET/PT) on FOX. L-R: Michael Lynche, Casey James, Katie Stevens, Lee DeWyze, Usher, Didi Benami, Crystal Bowersox, Siobhan Magnus, Andrew Garcia, Tim Urban and Aaron Kelly. CR: Michael Becker / FOX