Justin might not be best known for his comedic work, but Cameron says he'll be able to keep up with her and their co-stars.
"He's clearly a very talented comedian, look at his 'Saturday Night Live' [skits]," she continued. "He's fantastic, he's going to be so great."
Cameron told Access she had just finished her first day working on the comedy – which also co-stars Jason Segel, Lucy Punch, Molly Shannon and "Modern Family's" Eric Stonestreet – on Saturday.
"We just had our first day of shooting yesterday with Jason," she said. "And we just laughed all day. It's so wonderful, I'm so excited."
See more Access interviews from the Oscar red carpet, HERE!
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