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Lady Gaga and Christina Aguilera are making pop music history.  On Tuesday's season finale of "The Voice," the two stars shared the stage for the first time ever.  Aguilera surprised viewers by coming out from behind a giant seashell during Gaga's "Do What U Want." 

The ladies came together after the song and spoke to host Carson Daly about why they wanted to work together.  Christina said that it was actually the first time they had met face-to-face, and called Gaga "the most down-to-earth, real person [she's] ever met in this business." 

Gaga said that when "The Voice" called her, she was the one who asked if Christina would like to share the stage.  Though they'd never met, the ladies do share some history!

[HD] Lady Gaga & Christina Aguilera - Do What U... by IdolxMuzic

But the Mother Monster wasn't the only star power on the "Voice" finale, which crowned Team Adam Levine's Tessanne Chin. OneRepublic performed "I Lived," and its frontman Ryan Tedder also co-wrote Tessanne's new single, which she sang after her victory.

Before the announcement, she also got the chance to sing with her personal idol - Celine Dion. Celine brought Ne-Yo to the show to sing their duet "Incredible." Paramore performed their new single "Ain't It Fun" with finalist Jacquie Lee, and Aloe Blacc sang his Avicii hit "Wake Me Up" with finalist Will Champlin.

What a night!