Los Angeles - The nanny most decidedly did not wear Prada.

The Nanny Diaries, the boss-from-hell tale that preceded The Devil Wears Prada in print but followed it to big screen, didn't come close to matching Devil's box-office might, thanks to an unfashionable $7.8 million opening weekend, per Exhibitor Relations Co. estimates.

"This is a book that took the literary world by storm, but filmdom is another story entirely," Exhibitor Relations' Jeff Bock said Sunday.

Based on the 2002 bestseller, The Nanny Diaries, starring Scarlett Johansson as the titular child-care provider, posted the second-weakest opening of any new movie bowing on more than 1,000 screens. Only Resurrecting the Champ, a drama starring Josh Hartnett as a sportswriter on a mission to save boxer Samuel L. Jackson, was more punchless, scoring $1.8 million at more than 1,600 theaters.

While Johansson trumped Hartnett, her former onscreen and offscreen costar, in the weekend box-office standings (Nanny placed sixth; Resurrecting the Champ didn't crack the top 10), there was little else to cheer.

The Devil Wears Prada, the 2006 Oscar-nominated comedy to which The Nanny Diaries was inevitably and oft-unfavorably compared, was a bona fide box-office hit, earning $27.5 million in its opening weekend and going on to gross $325.5 million worldwide, according to Box Office Mojo stats.

To Bock, the big-screen Prada, based on the 2003 bestseller, had a couple of key advantages over the big-screen Nanny Diaries: namely, a star named Meryl Streep and a marketing campaign that, unlike The Nanny Diaries', worked.

Bock faulted MGM and Weinstein Co. for an early Nanny Diaries trailer that sold the movie as a run-of-the-mill romantic comedy rather than a smart movie for grown-ups.

"I think they missed the boat marketing to that demographic—the more upscale market," Bock said.

And the 22-year-old Johansson arguably missed the boat on becoming a bigger star. The Nanny Diaries' subpar performance, according to Bock, "will probably prove she cannot carry a film on her own yet."

At least The Nanny Diaries has company in the misery department. The summer has been a tough one for movies fronted by females. (Note to moviegoers: Females are the ones who play the hot girlfriends and/or supportive wives.) Georgia Rule (Jane Fonda, Lindsay Lohan, Felicity Huffman), No Reservations (Catherine Zeta-Jones) and Nancy Drew (Emma Roberts) were no match for the likes of Transformers. Adding insult to ignominy, aside from the indie hit Waitress, which has generated award-show talk for Keri Russell, the most notable female part of the season went to a man (John Travolta in Hairspray).

Overall, the boy-led Superbad ($18 million; $68.6 million overall) hung on to the top spot in the weekend rankings, despite or in spite of the requisite ticket-sales nosedive of nearly 50 percent.