Adam Levine had a tough decision to make on ‘The Voice’ tonight (Oct. 16), when Alessandra Guercio and Kayla Nevarez faced off with a duet of Katy Perry’s ‘Wide Awake.’

Both singers are only 17 years old and proved to be a good match for each other. When picking contestants for a battle round, “you want them to be able to connect with each other to a certain degree,” coach Levine explained.

During rehearsal, the girls showcased powerful vocals, but they both had their issues as well. Guest mentor Mary J. Blige recognized Guercio’s tendency toward perfectionism but reminded her to relax and explore the style of the song. Levine then criticized Nevarez for being slightly sharp on some of the notes.

When their performance was over, there still didn’t seem to be a clear winner. “Dang Adam, this is a sucky one for you because I really, truly believe that this was neck and neck,” Blake Shelton remarked. Christina Aguilera couldn’t decide on a favorite either, but she offered several words of advice to the young singers. She told them not to be afraid to take risks and to “really tap into exactly, uniquely who you are.”

Levine was torn, but he ultimately decided that Nevarez was the winner. While Guercio had her strong moments, her voice still sounded a little too trained and she seemed to lack self-confidence onstage.

Strangely enough, it was that apparent lack of confidence that saved her from elimination. Minutes after Nevarez was named the winner, Aguilera hit her buzzer to steal Guercio from Team Adam. “I just want to support you,” she said. “No woman should feel unconfident on any level.” Coming from a trained background herself, Aguilera can personally relate to Guercio and believes she’ll be a good fit for her team.