When The Voice coaches heard first sisters Whitney and Shannon trading lines of "Landslide" in their blind audition, they had no idea what they were in for. Soon enough the ladies sang together, and it was magic.

The women shocked coaches Miley Cyrus, Blake Shelton, Alicia Keys and Adam Levine when they took the stage, not only because there are two of them, but because of their flawless harmonies and delicate treatment of the poignant song, which they said they modeled after the Dixie Chicks’ cover. Originally sung by Fleetwood Mac, "Landslide" also became a hit for the Chicks in 2003.

It was Shelton who asked which version they were performing, noticing a hint of country in their style and praising their tight harmonies.

"It's that thing that you can only have, I truly believe, with siblings. Being a duo and being successful on this show has only ever happened one time," he said. "And I'm proud to say it was on my team and it was with the Swon Brothers. I want you guys to think about that because nobody works harder, I'd like to say, in the country music industry than me. I would be honored and proud to be your guys' coach."

Cyrus added that she adores the song and it has gotten her through many tough moments in her life — not to mention the fact that she grew up on country music like the Dixie Chicks.

Though Cyrus and Shelton have been duking it out for country artists this season, Keys and Levine make great cases for their own teams. The clip ends before the sisters choose their coach, but the full episode airs Monday night (Oct. 3) on NBC.

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