The teen did it his own way, inserting a new groove, style and some low, low notes.
She also shared why she was nervous working alongside him after they got married.
Contestants Omar Jose Cardona and Lana Love went head-to-head on a Frozen track.
Camila Cabello made a surprise choice during the Battles.
The performance got a standing ovation from Legend himself.
John Legend had to choose between two outstanding performances.
Coaches Gwen Stefani and Blake Shelton got in a (lighthearted) spat over one of the contestants following a stunning rendition of a Stevie Nicks duet.
With the lights a little brighter in the Battles, and the pressure ratcheted up a notch, one singer impressed.
"We're all going to miss him," Legend shared.
We don't know who Blake Shelton chooses as the winner, but Camila Cabello says she would "steal both of you" either way.
