While Britney Spears is "not a girl, not yet a woman," Christina Aguilera is of legal age and ready to get down 'n' dirty.

In mid-September, Aguilera will drop "Dirty," the first single from her still-untitled fourth record, which is now scheduled for release in late October. The song was produced and written by Aguilera and Rockwilder (who co-produced last year's hit remake of "Lady Marmalade") and features rapping by Redman, a publicist said.

At the end of the month, the brazen pop songstress will shoot a video for the track in Los Angeles with "Lady Marmalade" director Paul Hunter, who has also worked with Eminem, Jennifer Lopez, Mariah Carey and Lenny Kravitz. Aguilera's label said that Redman will appear in the clip but would not reveal any additional details.

Aguilera worked with a host of writers and producers on her upcoming record, including Glen Ballard (Alanis Morissette), Linda Perry from 4 Non Blondes (Pink), Eminem accomplice Scott Scorch, Eve, Dave Navarro and Alicia Keys, who co-wrote and co-produced the song "Impossible" (see [article id="1455399"]"Christina Aguilera, Alicia Keys Party Up For 'Impossible' "[/article]). Aguilera wrote or co-wrote nearly every song on the album. ([article id="1455405"]Click for photos[/article] of Aguilera in the studio with Keys.)

"I was very impressed by the fact that she has taken the role of being a writer quite seriously and really applied a lot of effort and class in drawing from her own inspiration," Ballard said of Aguilera. "I think she's a wonderful writer. We already know she's a great singer, but I think we'll be able to add to that. She's a really incredible writer."

Aguilera worked on the album, which is the proper follow-up to her 1999 self-titled debut, at various studios, including Electric Lady in New York and Conway in Los Angeles. She's currently narrowing down the disc from 20 songs to a more manageable number. Leftover tracks will likely appear on B-sides and soundtracks, one of her representatives said. ([article id="1456915"]Click for photos[/article] of Aguilera in the studio.)

Other song titles may include "Beautiful," "Fighter," "Infatuation" and "Can't Hold Us Down," a rousing track inspired by the verbal abuse she has received from Eminem and Limp Bizkit frontman Fred Durst.

For a feature interview in the studio with Christina Aguilera, including previews of songs in progress, check out [article id="1452715"]"Christina Aguilera: Not Your Puppet"[/article].