Casey Weston of Adam Levine's team stepped out of her country-ballad comfort zone to take on KT Tunstall's up-tempo rock number 'Black Horse and the Cherry Tree' on 'The Voice' tonight.

Weston, who defeated Tim Mahoney last month in the battle rounds, wanted to turn the song into a slow number. However, Levine insisted that she make it "energetic."

"It's gonna be a whole different side of me that I'm gonna have to learn how to show," admitted Weston.

Armed with an acoustic guitar and sporting a sparkly dress, Weston delivered a rockin' version of Tunstall's hit. She was flanked onstage by a couple of backup singers and three bucket-playing percussionists for the performance.

Christina Aguilera told Weston that she has "a beautiful voice," but added that she was sometimes overpowered by the background singers. Levine told Weston that he knew that she was out of her comfort zone, but that "it was amazing."

Watch Casey Weston Perform 'Black Horse and the Cherry Tree'