Alicia Keyshas selected Mendes, 19, as her celebrity adviser for the upcoming season of The Voice, making him the youngest star to ever fill that role.
"I was like, I feel like I should be getting in front of the microphone and singing, and asking her for advice," Mendes mused when ET joined them on set earlier this month. "I think there was one moment that I was sitting there halfway through a song and I'm like, 'Am I really sitting here right now with her being an adviser? I'm 19 years old!' So this is really crazy."
Keys says that with two albums and a slew of pop hits under his belt already, Mendes has "great experience" to bring to the table.
"He himself is a songwriter, a musician, a producer, and I think that's really valuable to [the artists]," she says.
"Yeah, the age too," Mendes admits. "There are some young people on this team and I think it's nice to hear from somebody really close to your age, being like, 'I have the same feeling,' you know? One thing we both said is, you don't get onstage, you just do -- you have to kind of think about it and it's hard work. You have to make it amazing and you have to believe in yourself, and I think them hearing that from both of our angles is really helping."
The Voice season 14, premiering Feb. 26 on NBC, marks Keys' third time around in a big red chair. She previously coached her team into the finals in season 11 and won the whole thing with Chris Blue in season 12. Now, Keys speculates that she may be working with "the strongest [team] I've ever had."
"It's all about passion. I think it's all about touching people," she says of her strategy to win. "I think that's why everybody loves this show, it's about real bona fide artists and talent out here showing you what they have, and you're like, 'I'm invested. I want you.'"
And, yes, Keys admits she's ready to compete -- especially with Blake Shelton.
"I really like Blake a lot and we get along so well, and he was just so crushed that I beat him so thoroughly when I did. I hope to be able to experience that again," she said with a laugh. "I have to come back and put him in his place, man."