Watch Adam Levine and Gwen Stefani Bring Ballad 'My Heart Is Open' to 2015 Grammys

Gwen Stefani and Adam Levine perform on stage at the 57th Annual Grammy Awards in Los Angeles on Feb. 8, 2015. 

It was time for a lover's ballad at the 2015 Grammys, and the sharply-dressed pair of Maroon 5's Adam Levine and Gwen Stefani fit the bill. Their familiar voices combined for a performance of the stripped-down piano ballad "My Heart Is Open," off Maroon 5's 2014 album V.

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The pair of Voice coaches performed in classic evening attire in front of a string-laced, orchestral backing, ready to let those feelings out. As the bows flared behind them, Levine and Stefani let their voices go to work.

It wasn't Maroon 5's usual funk-pop and it's a far cry from No Doubt's rock; what do you think of their grown up vibes? Who's voice dominated the duet?