Look out, Naomi.

While AnnaLynne McCord waxes poetic about Chuck Bass and a possible Melrose Place crossover, 90210 is planning a new nemesis for her character.

The show has signed up former Law & Order actress Elisabeth Rohm as a guest star for the fall. She'll appear in at least one episode as a bitchy socialite that locks horns with Naomi.

Over a man? We'll have to wait and see. But what else could it be, right?

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.