During Monday night's penultimate show, Levine threw his support behind Danielle Bradbery, the 16-year-old country singer from Texas who is on Blake Shelton's team.
After she performed her "defining moment" song, Levine explained why he thought she should win.
"The crazy thing about your voice is it's just so unbelievably perfect and powerful," he said. "It's one of the better voices I think I've ever hear live."
"And I'm just going to go ahead and say, I think Danielle's the winner of this thing," he said. "I think you're one of the most important artists we've ever seen walk across this stage."
Shelton then gave his fellow coach a standing ovation.
The whole exchange was even more unexpected given Levine and Shelton's -- mostly playful -- rivalry on the reality show. The two have all the previous winners of "The Voice" between them -- Levine's artist took the trophy Season 1, while Shelton has won the second and third seasons.
The final episode of "The Voice" will crown its fourth season champion Tuesday night.