Kelly Clarkson - Kelly Clarkson Celebrating 30th Birthday Today

For some of the contestants, the chance to sing and perform live with Kelly Clarkson will be a life-changing experience. This is, after all, the vocalist that impressed the whole of America, if not the world, with her faultless rendition of 'Star Spangled Banner' at last year's Super Bowl; it's one of the biggest gigs in America's sporting calendar and Clarkson pulled it off with aplomb, succeeding where many before her have failed.

Kelly certainly ended her twenties in a celebratory fashion. She was one of a list of legendary singers that took to the stage for VH1 Divas and last October, released her fifth studio album, entitled 'Stronger.' The song 'What Doesn't Kill You' was featured on Glee and the album sold 163,000 copies in the first week of release.