Blame it on the hormones: knocked-up superstar Julia Roberts is allegedly hopping mad that Catherine Zeta-Jones has been given top billing on posters for upcoming stinker Ocean's Twelve.

Julia, who is expecting twins in January, was aghast when she saw that Zeta-Jones was listed fourth on the poster, right after George Clooney, Brad Pitt and Matt Damon, while the Pretty Woman's name was tucked in, almost as an afterthough, at the bottom underneath Andy Garcia, Don Cheadle and Bernie Mac. That's right! Underneath Don Cheadle! In a way, you really can't blame poor Jules.