Demi Lovato brought it in an epic “Diva Riff-off” and crushed her competitor James Corden who said “I’ve got hits from before you were born!”  But Mr. Carpool Karaoke couldn’t hold his own against the ‘Confident” singer on Wednesday’s “Late Late Show”.  The show’s You Tube page sets it up for us: Demi Lovato takes exception to James Corden’s claim that divas such as Cher, Aretha and Tina Turner are more fierce than today’s divas, and the two decide to settle it in a Riff-Off featuring songs from Adele and Katy Perry, with some backing vocals from Level. MORE