Who’s that girl? It’s Dee!

It's Always Sunny in Philadelphia star Kaitlin Olson will have a recurring role on New Girl.

She will play “Ashley,” Jess’s (Zooey Deschanel) high school rival. To make matters worse, she’s also Jess’s Dad (Rob Reiner) fiancee.

Olson won’t be Jess’s only trouble this season, as she’ll have to duke it out with Jessica Biel, who will be guest starring as a “sexy scientist” possibly preventing a "twirly" Jess from gettin' laid.

The fourth season of New Girl starts in September.

[via The Wrap]