Actress Jessica Biel will guest-star in the Season 4 premiere, and her character won't find a friend in Jessica Day, TVGuide.com has confirmed. Biel will play a sexy scientist named Kat who fights with Deschanel's character over the same guy.
In the episode, the roommates will have a competition to see who can score at the last marital bash of the wedding season. Naturally, adorkable Jess wants to hook up with the man who is also being pursued by the "hottest scientist in the world."
It will be a long overdue return to television for Biel, who starred in "7th Heaven" in the late 1990s and early 2000s. Biel made a cameo on "Saturday Night Live" in 2009, but has mostly focused on film, with roles in "Total Recall," "New Year's Eve," "The Illusionist," and "Playing for Keeps."