'The Voice': Why Kelsea Ballerini Is Coaching Kelly Clarkson's Team During Battle Rounds

When Kelly Clarkson fell sick during season 20, she called up her pal to sub in!

When Kelly Clarkson got sick during season 20 of The Voice, she knew just who to turn to!

The singer, Emmy-winning talk show host and Voice coach fell under the weather during the filming of the season 20 Battle Rounds, and last week, her celebrity substitute was revealed to be none other than....Kelsea Ballerini!

"Just pretend I'm Kelly," the country star said in a promo for the season 20 Battle Rounds, proving that she's got Kelly's spark when it comes to landing steals and taking shots at fellow coach Blake Shelton: "Hey Blake, have I ever told you that you look like my dad?"

"Thank you so much @KelseaBallerini for sitting in for me while I was feeling under the weather!" Kelly shared on Twitter. "I know my team is in great hands with you!! Y'all aren't going to want to miss this!! The battles start next week on @NBCTheVoice! #TeamKelly #TheVoice."

"When @kellyclarkson calls and asks you to keep her seat warm, you put all those years of being her super fan to work," Kelsea shared on her own Twitter. Thank you @johnlegend, @nickjonas and ole pops @blakeshelton for making me feel like part of the @NBCTheVoice family."

Kelsea has plenty of experience with the singing competition show. She served as a fifth coach for singers on season 15's "Comeback Stage" segment and was Team Kelly's celebrity mentor during season 16. 

ET spoke with Kelsea ahead of the season 20 Battle Rounds, and she detailed how her last-minute involvement in this season of The Voice came together in "the biggest whirlwind" when Kelly fell sick.

"I was home in Nashville and got a text from Kelly at like 9 p.m., like, 'Hey, girl... I'm not feeling well. I don't have COVID, but with the protocols, don't feel safe going to set, could you cover the Battle Rounds for me?'" Kelsea recalled, noting that saying yes meant she had to be in Los Angeles the next day to start filming. "So I got on the plane, studied everything and watched everything. Landed, hair and makeup, set, said hi to Nick Jonas and John Legend and Blake Shelton, got in Kelly's seat and said, Fake it til you make it!'"

Thankfully, Kelsea had some kelp from Kelly herself, who was watching a livestream of the Battles and texting her notes, "and picking on Blake the whole time," she added with a laugh.

"I really enjoyed it," Kelsea shared, though she couldn't tease much about what moves she got to be a part of on Team Kelly. "I didn't have the time to get nervous, 'cause it was so quick, and that's good for me. If I know something's coming up, I mull over it and I get so nervous and anxious, so it was actually a real blessing. But yeah, I really liked sitting in the seat, I'm not gonna lie."

The Voice airs Mondays at 8 p.m. PT/ET on NBC. See more from the season in the video below!