Sara Bareilles is an overnight sensation. It's just that, in her world, that night took about six years to happen.

The 28-year-old Eureka, California, singer's piano ballad "Love Song" has become a radio staple after selling more than 1 million downloads thanks to a widely seen Rhapsody commercial. But nine months after her major-label debut, Little Voice, was released, Bareilles said it hardly feels like things are happening too fast.

"I don't feel that at all," she said. "I was very surprised when we were on 'TRL' at all, but the whole time I was wondering, 'What am I doing here? This is crazy.' It happened relatively quickly, but we've been doing this for such a long time. It's been six years in the making, so I'm really glad we're at a point where people are connecting with the music on a greater scale."

Now drawing comparisons to everyone from Sheryl Crow to Fiona Apple, the Broadway musical fanatic got bitten by the singing bug while performing in community and high school productions of "Little Shop of Horrors." After graduating college she spent many nights singing at open mics while waitressing on the side. Her hard work paid off with an Epic Records deal in 2005. She spent most of the next year writing and working on the songs that would make up Little Voice, which took almost another year to finish recording with producer Eric Rosse (Tori Amos).

Though Bareilles was initially reluctant to work with Rosse, their close studio relationship helped craft the emotionally charged songs on the album. "He was supposed to be a potential co-writer, and I had been asked to at least entertain the idea of doing some co-writing for the album, and I told them ahead of time that I absolutely hate co-writers, but I would try," said Bareilles. "And then I met Eric, and he was really soft-spoken, and he wasn't overbearing and he wasn't trying to coerce my ideas in any way, and we didn't end up co-writing together, but it became this very comfortable relationship where I felt like we could actually dive into this music, and it turned into a producer-artist relationship."

While some have pegged the frustration in the lyrics to "Love Song" as a veiled reference to the singer's struggle to deliver what she thought her label wanted ("I'm not gonna write you a love song/ 'Cause you asked for it/ 'Cause you need one, you see"), Bareilles said the real explanation is a bit more complicated.

"They had encouraged me to keep writing, and I just wasn't having any luck, and I was turning in the beginnings of ideas and snippets of moments of a song, and I was just getting a really sort of blasé reaction to everything," said the singer, who has had no formal musical training but always had a piano to plink around on at home. "I started to get really insecure about it, and then I got really pissed off at myself for caring what anybody thought. ... I went to a rehearsal space one day. I sat down and wrote something for me. And 'Love Song' basically wrote itself. It's totally honest, and I'm very lucky the label liked it as well."

Though she's just now going through the tumultuous ups and downs of being a star, Bareilles said she had some sense of what was in store for her after watching her pals in Maroon 5 go through it. She met the band when she was in college and they were still playing house parties under the name Kara's Flowers.

"We always saw big things for them, and I'm not surprised at all that they are the smash sensation that they are," she said.

Last year, while opening for "the boys," as she calls Maroon 5, the band gave newbie Bareilles a proper hazing during a show in Philadelphia. "I was at the very end of 'Love Song,' and I see something in my peripheral vision," she recalled. "I thought it was something falling from the rafters. ... The whole crowd started screaming, and three of the boys ran onstage in their underwear. I stopped playing and cringed down. I ended the song halfway through and was mortified for the entire set."