Though the two are longtime friends, they mean business when it comes to competing against each other on the singing competition series as coaches.
“Make no mistake, Kelly is my friend,” Shelton, 41, tells PEOPLE exclusively of the Voice newbie, 35. “But when she’s on this show, she is my enemy.”
Clarkson, who loves that she’s “a threat” to him, first appeared on the show as Shelton’s celebrity advisor during season two. Her husband, Brandon Blackstock, is also Shelton’s manager — but she says he’s not taking sides.
“He’s like Switzerland,” she says. “I always do say though that at least I put out — so unless he’s doing something I don’t know about, I should win!”
Shelton adds, “If I fire Brandon, it’s one thing. If she fires him, it’s going to be real bad. He knows who to suck up to.”
While he might not entirely have Blackstock behind him, Shelton definitely has a fan in Clarkson’s daughter, River Rose, 3.
“My daughter loves Blake,” Clarkson says. “He has this gravitational pull. I’ve even seen him with [his girlfriend] Gwen [Stefani]‘s son Apollo and her kids, and he’s like this tree that they all climb on.”
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When it comes to taking advice from Shelton — who has won the show a record six times — Clarkson says she looks to his actions as inspiration instead.
“He makes jokes but he really does help people after the show, and I’d like to do that as well,” she says before adding, “But he will mess with me left and right!”
Despite Clarkson’s appearance on the show, Shelton’s long-standing rivalry with fellow coach Adam Levine is still alive and well.
“Blake will never admit to this, but he says things that are straight up deceptive,” Levine says. “The [other coaches] know they’re not getting that with me. They know that I have a sort of forced honesty. It’s my blessing and my curse.”
It seems one of the common causes the coaches will be getting behind this season is beating Shelton.
“Blake has had his time in the sun,” Levine says. “But it’s time for someone else to shine. Let’s get Kelly a victory.”
“As long as Blake doesn’t win, we’re all happy,” Alicia Keys agrees. “We’re ready for a change!”
The Voice season 14 premieres Monday at 8 p.m. ET on NBC.