Kelly Clarkson may have been out sick during filming for The Voice's latest episode that aired on Monday night (April 12), but her country-leaning team members Kenzie Wheeler and JD Casper were in good hands.

Substitute coach Kelsea Ballerini filled in, mentoring the two would-be Voice champs through a Battle Rounds performance of the Nitty Gritty Dirt Band's country classic, "Fishin' in the Dark."

Wheeler brought classic country baritone to the stage during the duet performance, delivering the kind of rich vocal tone that has made country acts like Scotty McCreery and Josh Turner famous. Casper, meanwhile, not only delivered expert higher harmony, but he wrangled multiple instruments onstage, rounding out his vocal performance with acoustic guitar and a suitcase kick drum.

Before Ballerini made the official decision of which contestant will be moving forward, her fellow The Voice coaches weighed in with praise for both artists. John Legend and Nick Jonas both praised Casper's individuality, while Blake Shelton felt he'd bogged himself down by trying to negotiate multiple instruments onstage. Meanwhile, "it felt like Kenzie absolutely dumped himself into that vocal performance, so I would go with Kenzie," Shelton added.

"JD, the song choice might've favored Kenzie a little bit more, but you're still standing there doing 18 million things at once. So that's really amazing," Ballerini reflected when it came time for her to pick a winner. "And Kenzie, I just don't think you know how good you are. And I think it's a really, really wonderful compelling thing about you as an artist. I hope you never know how good you are."

"And I also hope you never shave the mullet," Ballerini joked, asking the young singer to pinky-promise her he'll never change his hairstyle.

All jokes aside, Wheeler's soulful vocals and expert delivery ultimately won out: Ballerini named her the winner of the Battle Round, meaning he'll move ahead to the Knockouts round.

Now in its 20th season, The Voice concluded its Battle rounds on Monday night. Next up, during Knockouts performances, contestants will select a song of their choosing in hopes of advancing to the live shows. Knockouts begin on Monday, April 19 at 8PM ET on NBC.

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