We've all been salivating for "Sin City 2" to begin filming, already -- but according to Rosario Dawson, it's gonna have to wait until pregnant Angelina Jolie has her baby this summer.

Speaking to Sci Fi Wire, Dawson -- who, like many of the surviving cast members of "Sin City," is attached to come back in the sequel -- said that production was on hold while co-director Robert Rodriguez waits for his dream leading lady, Jolie. If you've got your eye on the tabs you know that Jolie is holed up in a Paris high-rise with her kids Zahara and Maddox, as well as soon-to-be baby daddy Brad Pitt (we've been poring over People magazine's in-depth analysis of the pair's non-matrimonial "mystery" rings; he's wearing a gold band on his right middle finger, while she's MOVED hers from right index finger to thumb!).

But back to "Sin City 2." The sequel will pick up with two more of Frank Miller's pulp-noir stories, "Lost, Lonely and Lethal" and "A Dame To Kill For," and has "Sin City" stars coming back, including Clive Owen, Mickey Rourke, Jessica Alba, Devon Aoki, Brittany Murphy, and Michael Clarke Duncan.

From Sci Fi Wire: ""The film's been kind of postponed because Robert has been interested in Angelina Jolie for the lead," Dawson said in an interview. "But she's very pregnant right now. So that's putting an understandable hold on the film." "

Fans are speculating that the "lead" role Rodriguez is holding for Jolie is none other than Dwight's old flame Ava (the Dame in "A Dame To Kill For"). Jolie's supposedly due this summer, so we may have to wait a bit longer to find out for sure.

From Wikipedia: "Ava Lord, the dame to kill for. An ex-lover of Dwight McCarthy who manipulates men through her good looks and her supposed innocence. An expert liar, she is considered a goddess by Manute and a manipulative witch by Dwight. She represents the classic femme fatale, acting as a foil to Dwight's typically hard-boiled but cool-headed anti-hero."