Christina Aguilera, Demi Lovato debut diva duet at Billboard Music Awards

Anika Reed | USA TODAY

When you put Christina Aguilera and Demi Lovato together onstage, you can expect an electric performance.

And that's exactly what fans got at Sunday night's Billboard Music Awards when the two powerhouse vocalists united for a dynamic performance of their new feminist duet Fall In Line.

Decked out in all black trench coats and surrounded by military-style dancers, the divas belted out the rousing anthem from Aguilera's upcoming album Liberation live onstage for the first time.

Aguilera, 37, and Lovato, 25, lit up the stage with some of the strongest vocals of the night, trading vocal runs back and forth.

Lovato tweeted her thanks to her collaborator following the performance. "Thank you for everything," Lovato says in the tweet.

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Twitter was abuzz after their impressive duet, some hailing it a major success.

Singer Adam Lambert tweeted: "DRAMA. A MESSAGE. REAL TALENT. FIRE."

IM FULLY SLAIN OVER THAT @xtina @ddlovato DUET. VOCALZZZZZ. DRAMA. A MESSAGE. REAL TALENT. FIRE. — ADAM LAMBERT (@adamlambert) May 21, 2018

"Xtina and Demi giving you VOCALS," another fan said.

Xtina and Demi giving you VOCALS pic.twitter.com/di3jHjZMb5 — Ira (@ira) May 21, 2018

According to another Twitter user: "Demi and Xtina did THAT."

xtina trying to tell demi that she did good at the end of the performance i’m crying pic.twitter.com/c5G7k3mHqh — dom⛓ (@CMONPUDDlN) May 21, 2018

The performance wasn't the only thing people were talking about on social media. During Shawn Mendes's performance of In My Blood, the camera flashed to Lovato with what some fans said was a seemingly blank face.

One person said Lovato has "no chill" for her reaction to Mendes.

DEMI LOVATO'S REACTION TO SHAWN MENDES PERFORMING "IN MY BLOOD", YA'LL SHE HAS NO CHILL LMAOOOOO 😂😭😭💀💀 #BBMAs pic.twitter.com/7ySHbpYoiX — ɐɹǝʇnq💧 (@notearsbutera_) May 21, 2018

Another pointed out that Lovato's "face be looking like she don't care bout none of these people."

@ddlovato face be looking like she dont care bout none of these people Lmfaooo #bbma — Angel (@KissesA94) May 21, 2018

Lovato's facial expression got a few laughing emojis from other Twitter users.

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