The competition on The Voice is getting fierce.

So fierce, in fact, that  Ariana Grande took her playful rivalry with fellow coach  Blake Shelton all the way to Las Vegas last weekend, where the country singer's wife  Gwen Stefani was performing the final concert in her Just a Girl residency.

Blake took the stage with Gwen at one point to perform their 2020 duet, "Happy Anywhere," and as he exclusively told E! News' Daily Pop on Wednesday, Nov. 10, it was then that Ariana decided to take part in some good old-fashioned trolling.

"Afterwards, Ari was showing me on her phone that she was filming it and she was shouting, 'Look, everybody, my grandpa!'" Blake hilariously recalled. "And she was even doing the thing where you squish their head!"

The "God's Country" singer joked that the move should give The Voice fans a feel for "what happens when the camera is not on." 

For Ariana's part, she said all of the back-and-forth is "loving." 

Her fellow The Voice coaches  Kelly Clarkson and  John Legend agreed, telling E! News that they "all genuinely love each other." 

"Like, we're very supportive of each other," Kelly explained. "So that's why it's so fun to work with people like that, because then you can go at each other and you know at the end of the day, it's just for TV and we're being playful, but it's fun."

"It really is fun," John added. "It's fun to pick on each other, it's fun to be competitive with each other and we also really respect and love each other."

Perhaps Blake's just, as he put it, "an old grandpa" ready to retire from The Voice. 

"Something's got to give at one point," he said. "I'm running out of advice!"

Fans rooting for Team Blake shouldn't be too worried, though—he told E! News that The Voice shifting to a one-season schedule this year "really helps" a lot.

"Then I can watch the Home Shopping Network and all that stuff and really learn how to resell myself again, you know what I mean?" he quipped. "I feel like six months of watching that, I can kind of get back in the groove again and sell myself again as that vaporizer."