By Lenny Beer & Jon O’Hara

Last week’s chart debut for Arista’s Avril Lavigne at #8 was a highly unusual Top 10 bow from a new artist. But this week’s move up to #7 on the chart on a 14% increase in sales is just plain unheard of.

Lavigne is the latest arrival in a wave of similar female singer-songwriters including Michelle Branch and Vanessa Carlton, each of whom has opened the door a little bit more for the next. And as the massive teenpop audience matures and looks for something with a little more depth, each is playing a major role in capturing a part of that audience and gaining acceptance for their more intimate (yet still resoundingly Pop) music.

You won’t find any snakes on these girls’ shoulders. Rather than the glitz and spectacle that has powered the highly polished teenpop sensations, these new artists—each under 20—rely on their writing, performances and "real-girl" personalities to make a big impression.

But making that impression hasn’t been easy. When Branch’s The Spirit Room was released last August, she and label Maverick encountered more than a little resistance from both radio and retail, where Pop still meant boy bands and teen divas. But after an initial struggle, first single "Everywhere" grew at radio, went Top Five at MTV’s TRL and began to sell more quickly. Branch’s album is now Platinum.

"I think that Michelle has opened up a lot of doors for these artists," says The Firm’s Jeff Rabhan, who manages Branch. "When her first single came out, radio wasn’t interested in playing these kinds of artists. I think that she really has kicked the door open for Vanessa and Avril and, hopefully, for many more to come."

Enter A&M/Interscope’s Carlton, whose emotional, piano-driven compositions have elicited comparisons to Fiona Apple and Tori Amos. Her undeniable smash "A Thousand Miles" was the most-played record in the country by the time her album, Be Not Nothing, was released April 30, accompanied by an aggressive $3.50 retail rebate program. The startling video, which MTV went in on all the way, also dramatically increased awareness. The result? 107k in first-week sales and a #5 chart debut.

Observes A&M President Ron Fair, who, in addition to signing Carlton, signed Christina Aguilera while at RCA, "I would never denigrate Britney, Backstreet, NSYNC, or Christina, because pop music isn’t just one thing, and they’ve made a lot of great records. But each of these girls has a unique voice and approach—Vanessa with her classically derived piano, for instance. Pop is always changing, but it’s all related. Everything influences everything."

And now Arista’s Lavigne, a hugely appealing "sk8r" out of Napanee, Ontario, is taking it to the next level, gaining a huge radio audience for hit single, "Complicated," Buzzworthy MTV rotation for the video, and as we mentioned above, increased sales for album Let Go in its second week out.

"The first- and second-week chart success of Avril Lavigne is a clear indication that she has struck a responsive chord across a wide section of both teen and post-teen followers," says Arista President/CEO Antonio "L.A." Reid. "The reaction has just been amazing, and as others pick up on her music, they’ll discover an extraordinary voice on the threshold of an exciting career."

Adds Arista Sr. VP Promotion Steve Bartels, "I’ve always believed that hit songs, when showcased, come through. Just look at the success of Sarah McLachlan, then how Dido continued breaking ground and now this current progression. We believe Avril has four or five songs on her album that have huge potential across multiple formats."

Nettwerk’s Terry McBride, who manages Lavigne, concurs: "Avril is who you see—and never underestimate the kids to see one of their own. This album has been well set up using what we learned from building career artists like Sarah McLachlan and Dido: Make a great album with multiple singles, make sure you brand the artist to a Modern format, make it real and don't rush."

Maverick Sr. A&R Executive Danny Strick , who notes that Branch, Carlton and Lavigne are doing well at Adult as well as the more youth-oriented formats, sees minimal resistance ahead: "There may be more of an emotional connection, lyrically, and with the tenor of the production, but it’s still Pop," he says. "And someone can like Britney and like Michelle. That seems to be OK. It’s a really open audience, so now this wave of artists is tapping into it, and one by one, they’re definitely connecting."

Now that these three have pushed the door open, we’ll have to see how far this vanguard can take it—Branch is already writing her next record, which Strick says they hope to begin recording by year’s end—and how many others they inspire. Each of these young artists is poised to build a career, and we’ll be watching those careers closely.