Tori Kelly's single "Should've Been Us" is a giant hit, but that doesn't mean she's going with an all-out, crazy performance when she brings it to the 2015 MTV Video Music Awards on Sunday.

I caught up with Tori after her rehearsal on Friday (Aug. 28), and she confirmed that, yes, she's playing "Should've Been Us," and that she's really focusing on the music, rather than a huge production.

"My performance kind of came naturally this time around because I really wanted it to be about the music first," Tori said, wearing a flannel tied around her waist and the kind of smile you get when you've just hopped off the VMA stage. "Of course I know the song, because I've been performing it for so long, but I really just wanted it to be about the song and the music, nothing too crazy stage-wise, at least with props and stuff like that. I wanted to focus on the simplicity of the music and strip it back."

Kelly, who's still reeling from the release of her debut album Unbreakable Smile in June, said it didn't take long to plan out her performance. After all, she couldn't help but start dreaming it up when she got the phone call from manager Scooter Braun.

"I was like screaming internally," she said, recalling the day she learned she was performing at the VMAs. "I was just trying to process what I just heard. And I remember immediately going straight into focus mode. 'What am I going to do? What am I going to sing? How am I going to sing it? What am I going to wear?' All these things going through my head."

The singer will be joined by her band, but she added that there will be some more stripped-down parts to her set -- "I'm trying to give a full spectrum of what I'm about."

"I think there's something about the VMAs that I've always been so hyped about, even just watching them from home, growing up, there's just an epicness," she said. "It's so big, and everyone just goes all out. Everyone expresses themselves and takes their personality and throws it way out front. So that is something I'm really looking forward to. I feel like when I get out on stage, I'm going to naturally give it 127 percent."

As for who she's excited to see during the show? She stoked for Britney Spears, Demi Lovato and, of course, Justin Bieber, who is performing "What Do You Mean?"

"I'm excited about Justin Bieber, he's performing his new song for a comeback moment," Kelly said. "I think he's gonna kill it. Demi's gonna kill it."