Cameron Diaz thinks her ex Justin Timberlake is perfect for 'Bad Teacher'.

The pair are to be reunited on the set of the comedy film, in which they will both play lead characters and the actress couldn't think of anyone better for the role.

Cameron said: "He's the best person for the job. He's going to be hilarious. He's clearly a very talented comedian; look at his 'Saturday Night Live' skits. He's fantastic. He's going to be so great."

The movie centers on a junior high school teacher who is dumped by her rich older boyfriend, only to turn their attention to a colleague.

Justin and Cameron dated for four years before splitting in 2007. The 29-year-old singer now dates actress Jessica Biel.

Other stars in the movie include Molly Shannon, Jason Segal, Eric Stonestree and John Michael Higgins.

Doug Belgrad, co-president of Columbia Pictures said: "With Justin, Molly and Eric, joining Cameron, Jason, Lucy and the rest of this dream comedy cast, we couldn't be more excited about this movie."

Filming began on Saturday (06.03.10), and the movie is set to be released in 2012.