"I loved how tightly-knit those harmonies were," Ariana raved, telling the trio she already had plans for songs she wanted them to cover. "My favorite part is vocal production, and adding all of these layers. That's like my dream, when you guys started, I was so surprised in the best way."
"I grew up singing with my family in Ohio," John said, appealing to the siblings' story. "I've arranged for a cappella and gospel, and so I've always loved what harmonies can do when they're done right."
Their pitches, however, fell short of Kelly's enthusiasm for the group, and -- despite Blake's best efforts -- Kelly landed Girl Named Tom to her team, kicking off the season 21 rosters with a three-for-one!
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'The Voice' Season 21: Kelly Clarkson and Jason Aldean on Their 'Eclectic' Team (Exclusive)
ET spoke with the coaches during their season 21 press conference ahead of Monday's premiere, where John, Kelly and Blake placed the target squarely on Ariana's back as the first-time coach this season -- especially because so many of the show's young singers idolize the two-time GRAMMY winner's vocal talent and chart success.
"Of course she's a threat!" John said with a laugh. "She is hugely talented, hugely successful and has legions and legions of fans that know how to use the internet and vote."
"There's no disadvantage when you're Ariana Grande," Kelly agreed. "She can't say it. I will."
"It's embarrassing to follow her [onto the Voice stage]," Blake joked of the audience's enthusiasm for the "7 Rings" singer. "It exposes my lack of celebrity."
As a longtime "huge fan of The Voice," Ariana was humble about her possible advantages, but said she couldn't wait for fans to see how her season 21 team comes together.
"I have watched many seasons and I love watching the show," she said. "It always has the best energy. It's such wholesome, inspiring television, and I love seeing the different voices and watching so many people start careers for themselves. It's a beautiful, amazing thing."
The Voiceairs Mondays and Tuesdays at 8 p.m. PT/ET on NBC. See more from season 21 in the video below!