To bring the house down, Lovato sang her own hit, "Heart Attack", which prompted Corden to declare her the victor. Yup, he replied, rattling off a list that included Turner, Aretha Franklin and Whitney Houston, who he insisted were fiercer than those of today.
However, Lovato was able to pull out a win when she countered with her own track, "Heart Attack" and then dropped the mic. Corden tried to go deeper with Tina Turner's "River Deep - Mountain High".
Arguing his point, the funnyman said: "They didn't have Instagram - they just had sass, voice, songs". "Divas back then were just better than divas are today". Demi then joined him to close out the sketch with Gloria Gaynor's "I Will Survive".
Always the diva, Lovato (literally) dropped her mic after coming out as the uncontested victor and asked that late-night host to pick it up. "Just really terrible, bad".
Before singing, he said: "You better watch your mouth. You need a little respect". "I've got hits of my own", Lovato shot back, before dipping into a killer version of Adele's "Rolling in the Deep".
"Can you just pick my mic up...b--", she told Corden.