See Blake Shelton's 'Voice' Team Sing Little Big Town, Reba McEntire

Brennley Brown and Lauren Duski face off in battle rounds with "Better Man," while Ashley Levin and Casi Joy get sassy on "How Blue"

'Voice' contestants Brennley Brown and Lauren Duski face off in the Battle Round with a version of Little Big Town's "Better Man."

Don't let Adam Levine's mocking jabs fool you – Blake Shelton is not messing around. And when the battle rounds kicked off last night on Season 12 of The Voice, Team Blake, along with some help from guest mentor Luke Bryan, was ready to assert its power.

First up were Brennley Brown and Lauren Duski performing Little Big Town's recent single "Better Man," penned by Taylor Swift. "Watching stars be born, I don't think that ever gets old," said Bryan during their mentoring sessions. "[With] Brennley ultimately your mind goes to artists like Taylor Swift when they just came out, and Lauren's voice has a lot of the same characteristics that Karen Fairchild has from Little Big Town. I really put them on an even playing field."

A natural on stage, 25-year-old Michigan native turned Nashville resident, Duski gave the song a real punch of emotion with her raspy chest voice and restraint. Her competitor Brown, a 15-year-old powerhouse from California, stood on equal footing with her contagious energy and dazzling mastery of scales.

Ultimately, the decision of who to keep left Shelton distraught: "I don't want to let either one of the two of you go. But I have to, and all this is going to boil down to is what I can envision moving forward with my team," he admitted. "This one hurts me. The winner of this battle is Lauren," he got out, with Gwen Stefani and Adam Levine immediately pounding their buzzers to steal Brown. Though Levine launched into an impromptu "Happy Birthday" to try and sway her to join him – with a dramatic pause for effect – Stefani ultimately secured her as a new team member.

Later, another standout performance came when two Nashville residents and traditional-leaning artists, Ashley Levin and Casi Joy, performed Reba McEntire's 1984 Number One "How Blue." Clearly, Shelton was gearing himself up for a difficult choice: "They've got that storytelling factor about them, it's gonna be an incredible performance. The thing that I love about Ashley's voice is the power – she commands the attention of the room. Casi's voice is that classic country sound that reminds me of Tammy Wynette," he commented during rehearsal. "It's gonna be a sick, sick feeling that I'm gonna have when I have to make this decision."

After the two competitors opened with a chorus of practically flawless harmony, Levin, 23, originally from Miami, impressed with her assertive vocal attack and effortless high notes. Meanwhile, Joy, 26, who hails from Kansas City, floored the judges with her uniquely sassy blend of growls and yodel-style pitch jumps. "You're both so talented, that I pray everybody stays on the show," said Shelton following their performance. Shelton ultimately picked Joy as the winner, but the other judges were not about to let Levin go home – eliciting a rare three-buzzer steal, she was wooed to join Team Alicia Keys. Watch it below.

The Voice battle rounds continue tonight, Tuesday, March 21st, at 8 p.m. ET on NBC.