ET caught up with the country star at the 2019 CMA Awards in Nashville, Tennessee, on Wednesday, where he reacted to the news that Nick Jonas will be replacing his girlfriend, Gwen Stefani, as coach after the show's current season wraps on NBC.
"He's going down!" joked Shelton, who attended the awards show with Stefani, and won Single of the Year for "God's Country," which he performed onstage. "He replaced my girlfriend and that's unacceptable."
"We're gonna settle this on the stage, coach to coach," he added. "He's going down."
Later in the interview, Shelton also had jokes when ET asked him about fellow Voice coach John Legend being named People's Sexiest Man Alive for 2019.
"I'm the one that broke the news to him on The Voice as a former sexy guy," replied Shelton, who previously held the title in 2017. "I told him afterwards, I said, 'Hey man, listen. After this announcement comes out, wait about two weeks before you look at social media. Because everybody that ever hated you is gonna have something to say about it.'"
And Shelton certainly isn't wrong! Just moments after he announced Legend's accolade during Tuesday's live episode of The Voice, the "All of Me" singer's outspoken wife, Chrissy Teigen, took to Twitter to get ahead of the backlash she knew her family would receive from social media trolls.
"I cannot WAIT for people to get mad about John being the sexiest man alive," she tweeted at the time. "It's my new Starbucks holiday cup."
"No don't send it to me please," she continued. "I like to see these people naturally, in the wild."