Popsugar Celebrity Celebrity Friendships Demi Lovato at Christina Aguilera Vegas Concert Photos 2019 Demi Lovato Was the Ultimate Superfan at Christina Aguliera's Concert: "Keep It Up Queen" 3 June 2019 by Brea Cubit First Published: 1 June 2019 View On One Page Photo 20 of 22 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 20 Previous Next Start Slideshow Celebrity FriendshipsCelebrity InstagramsDemi LovatoChristina Aguilera