Demi Lovato and James Corden had a riff-off after the host wagered that divas of the past, like Tina Turner, are better than divas of the present, like Adele.
For the riff-off, Lovato invited the a cappella group Level to back them both onstage. The "Confident" singer kicked things off with Adele's "Rolling in the Deep" before Corden launched into Turner's "River Deep — Mountain High." After throwing some playful insults at one another, Corden sang a bit of Aretha Franklin's "Respect," which Lovato countered with Katy Perry's "Roar" followed by her own hit "Heart Attack." In true diva fashion, she asserted her dominance over the riff-off by dropping her own microphone and demanding that Corden pick it up for her.
Corden subsequently has a crisis of his own diva-ness, questioning whether or not he is a good enough diva. Lovato reassures the host that he's a great diva before they belt Gloria Gaynor's "I Will Survive" together.