Twilight' Vs. 'The Hunger Games': It's War!

As the mega franchises prepare to battle at the box office this year, the two casts are squaring off behind the scenes in a smack-talking slug-fest!

OK! GALLERY: THE HUNGER GAMES STAR JENNIFER LAWRENCE STEPS OUT IN BEVERLY HILLS

Sources say Oscar-nominated Jennifer Lawrence has given Kristen Stewart the cold shoulder, calling the Twilight star "snooty," and talking smack. "When I heard Kristen Stewart say, 'I only read the first Twilight book,' I was like, 'Oh, man,' " says Jennifer, 21, "because she wasn't a huge fan of the books. I was like, for The Hunger Games book lovers I should probably read the books."

OK! NEWS: THE HUNGER GAMES STAR JENNIFER LAWRENCE DOESN'T WANT TO BE AS FAMOUS AS KRISTEN STEWART

"It's like part of Jennifer really wants to overtthrow Kristen as Hollywood's young darling, and she's more motivated now that their feud is pretty much out in the open," Jennifer's pal tells OK!.

In turn, Kristen, 21, like a good little vampire, went right for the virtual neck, biting into Jennifer's looks, branding her "plain," the pal says. "Jennifer isn't innocent, but it hurt when she found out what Kristen said," the pal says.