So how does Cameron Diaz feel about getting romantic — even if only onscreen — with ex-boyfriend Justin Timberlake? In a word: thrilled.

"He's the best person for the job. He's going to be hilarious," the actress told "Access Hollywood" host Billy Bush on the Oscars red carpet Sunday.

The former twosome are pairing up in the big-screen comedy "Bad Teacher," in which they'll play the leads. The film — which centers on a teacher (Diaz) who makes a play for her rival's boyfriend (Timberlake) after getting dumped — started shooting this month in Los Angeles. The comedy also stars Molly Shannon, Jason Segel, Lucy Punch and "Modern Family" actor Eric Stonestreet.

Variety reports that Timberlake was cast after Columbia Pictures saw his performance in the upcoming David Fincher film "The Social Network," based on the founding of Facebook. "To be honest, David Fincher is so ridiculously genius that we're all just following his lead," Timberlake has said. "I think we want to tell the story, and I want to tell it through [screenwriter Aaron] Sorkin's words and Fincher's eyes. I think the consensus for all of us is that we just want to make a great film."

Diaz, who said they just had their first day of shooting with Segel on Saturday, is ready to see Timberlake put his comedic chops to work. "He's clearly a very talented comedian; look at his 'Saturday Night Live' [skits]," she told "Access." "He's fantastic. He's going to be so great."

Check out everything we've got on "Bad Teacher."

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