'New Girl' fans rejoiced over Jess and Nick's fulfilled relationship back in Season 2, but now, it turns out that the couple's incompatibilities have sent the romance back to square one. Since they split up on the show, creator Liz Meriwether went on to excite viewers about a number of new possibilities, not only relationship-wise, but also on the characters' struggles to balance life, love, and career.

Actress Jessica Biel will star in a cameo role on the premiere episode together with 'It's Always Sunny in Philadelphia' actress Kaitlin Olson. Olson is back for her recurring character (Ashley), who is Jess's high school rival and her dad's fiancé. On the other hand, Biel is playing the role of Kate, a scientist who will serve as Zooey Deschanel's competition over a man.

"It's opening up a whole new area of stories with them being exes, which I think is like a really interesting, fun, new territory," Meriwether teased on the trailer video.

Deschanel chimed in and said, "Nick and Jess sort of realized that they're not as compatible as they might have thought."

The show explores how awkward the situations might be if two exes live under the same roof, who both are struggling in their early '30s to figure out life's choices. Scmidt is also set to make his first hilarious antic on the series that fans will not want to miss.

Other casts include Jake Johnson (Nick), Max Greenfield (Schmidt), Lamorne Morris (Winston), Hannah Simone (Cece), and Damon Wayans, Jr (Coach).

'New Girl' Season 4 premieres September 16, at 8 PM on FOX.