Justin Timberlake has signed on to star opposite his former real-life love, Cameron Diaz, in Columbia Pictures romantic comedy “Bad Teacher.” Shoot begins later this month.

“Modern Family’s” Eric Stonestreet and Molly Shannon have also boarded the project, which co-stars Jason Segel and Lucy Punch.

Story centers on a middle-school teacher who, after being dumped by her boyfriend, vies with a rival (Punch), who is dating the school’s model instructor (Timberlake).

Though Timberlake’s casting as the male lead may seem awkward — he and Diaz were a couple for four years and endured a breakup that played out exhaustively in the tabloids — the studio was eager to work with the singer-actor again after seeing his performance in David Fincher’s upcoming “The Social Network.”

Jake Kasdan is directing “Bad Teacher” from a screenplay penned by Lee Eisenberg and Gene Stupnitsky. Jimmy Miller produces.

Timberlake is repped by WME, Rick Yorn and Jennifer Davisson Killoran.