Folk duo Andi & Alex went up against powerful rock vocalist Blaine Mitchell Monday night (Oct. 26), battling it out in the Knockout Rounds to keep their spot on The Voice’s Team Adam. While Mitchell chose a dynamic indie rock tune, Andi & Alex kept it low key with their cover of Keith Urban’s “Stupid Boy."

The guest advisor this week was Rihanna, who may not be known for her country prowess, but had some insightful advice for the twin sisters. She encouraged the young ladies to explore the stage on their own and turn away from one another as if they were singing in separate bedrooms.

“It’s almost like you’re afraid of your own voice,” she said. “You have to be bold."

The girls took that advice and ran with it, showing they each had unique voices and could own the stage by themselves, as well as together. They began the song alternating lines, giving Andi, who usually sings harmony, a chance to let her voice shine, as well. But it’s the duo's trademark harmonies that continued to impress coach Adam Levine.

“Their harmonies are like God-sent,” he gushed. “It’s like listening to angels."

The performance was a soft, emotional take on the song, typically sung by a male, with a folk twist that impressed not only the audience but all four judges — they gave the sisters a standing ovation.

Though he clearly loved the delivery, coach Levine couldn’t move past Mitchell’s explosive cover of James Bay’s “Hold Back the River” and chose the opponent for the spot in the Live Playoffs. Resident country coach and fan of the duo Blake Shelton seemed like an obvious match for a steal, but ended up letting Andi & Alex go.

“I only have one steal, so I’m being really picky,” he explained.

Check out their moving performance of Urban’s hit above.

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