Demi Lovato confronts James Corden in fierce Diva sing-off

When singer Demi Lovato hears James Corden say divas today are not as good as divas of the past, she decides she wants to settle things. And what better way to fight it out than with a Divas Riff-Off.

As James brings out Cher, Aretha and Tina Turner, and Demi backs herself up with Adele and Katy Perry, watch as one diva reigns supreme.