Hours before the premiere of [movie id="434956"]"Michael Jackson's This Is It,"[/movie] Orianthi, Jackson's guitarist for the planned London concert series, stopped by MTV's "It's On With Alexa Chung" to chat about MJ and her brand-new album, Believe. Of course, being a rock star, she also took some time to bust through her first single, the guitar-driven pop tune "According to You."

Before stepping in front of the mic for her live performance, though, Orianthi spoke about what it felt like to perform alongside the superstar. "It was just insane," she said. "When I was up on the stage with him, it was just surreal."

She also made clear that while Jackson was the King of Pop, he had absolutely no ego, as far as she could tell. "He was really personable, and he would speak to every one of us," the Australian 24-year-old said. "He was so encouraging. He just wanted us to step out and do our best and not be nervous. It was an awesome experience."

She then ripped into "According to You," one track on what Orianthi described to us as a radio-friendly album with a throwback vibe. "It's got a real '80s, now, rock vibe to it," [article id="1624777"]she told MTV News in an earlier interview[/article]. "There's a guitar solo on every track. It's bringing the '80s back, in a way. I just love that music."

On Wednesday, "This Is It" will open for a limited theatrical run, giving audiences an inside look at Jackson's final days. Orianthi has fond memories of those days. "He was like a big kid, and he wanted to have fun," she told us. "The last couple of nights we rehearsed with him, he was just in great spirits, and he was just so happy with the way everything was coming together. And you could just tell he was so excited with this vision."

Don't miss the [article id="1624819"]"Michael Jackson's This Is It" premiere special[/article], airing on MTV and VH1 tonight at 8:30 p.m. ET! "Michael Jackson's This Is It" opens for a limited engagement on October 27 and wide on October 28.

Check out everything we've got on "Michael Jackson's This Is It."