Johnny Galecki and Sara Rue, The Big Bang Theory

When is perfect sitcom casting Less Than Perfect? When it involves Sara Rue.

The well-regarded comic actress has been tapped for a multi-episode run on CBS' red-hot series The Big Bang Theory, executive producer Bill Prady tells TVGuide.com exclusively.

Rue will play Dr. Stephanie Barnett, the brand-new girlfriend of one Big Bang boy, who in short order is "stolen" away by another.

On the losing end of the deal? Wolowitz. On the winning end: Leonard.

Since wrapping up her four-year run as the lead of ABC's Less Than Perfect, Rue has appeared in numerous TV movies and has guested on series such as Two and a Half Men. Her first Big Bang episode is scheduled for Nov. 17 and it is hilarious, I am told.

For much more on The Big Bang Theory, which this past week hit a series high in ratings — even besting Dancing with the Stars in the demos! — read my in-depth Q&A with Prady coming Monday.

Crave TV scoop? E-mail Matt and Mickey at mega_scoop@tvguide.com.