Christina Aguilera and Demi Lovato united for a dramatic, authoritative performance of their collaborative single "Fall in Line" during the Billboard Music Awards.

"Fall in Line" is a slow, heaving ballad, with plenty of opportunities for vocal acrobatics for Aguilera and Lovato. Both singers were dressed in shiny black leather like Nineties action movie stars, roaring the defiant lines – "I got a right to speak my mind/ ... I wasn't made to fall in line." The two women ended the performance in an embrace, with their foreheads touching.

"Fall in Line" os a single from Aguilera's upcoming album Liberation, out June 15th. The self-empowering track is the third sample from the LP, following the ballad "Twice" and the Kanye West-produced "Accelerate" with 2 Chainz and Ty Dolla $ign. Aguilera, who performed "Fall in Line" with James Corden recently on "Carpool Karaoke," will promote her new record on an upcoming North American tour – her first in over a decade – featuring Big Boi as special guest.

Lovato has remained busy since issuing her sixth LP, , in September 2017, and much of her output has come in the form of collaborations like "Fall in Line." She teamed with "Despacito" star Luis Fonsi for an English rework of their single, "Échame la Culpa," joined former tour-mate DJ Khaled for "I Believe" from the A Wrinkle in Time soundtrack and covered Elton John's "Don't Go Breaking My Heart" with Q-Tip.