EXCLUSIVE: Jennifer Aniston Reveals Why She's Intimidated by Her Pal Julia Roberts

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Even big-name celebs can get star-struck sometimes. For Jennifer Aniston, it happened when she got the chance to work with Julia Roberts.

The former Friends star walked the red carpet at the premiere of her and Roberts' new film Mother's Day at the TLC Chinese Theatre in Hollywood on Wednesday, where the 47-year-old Golden Globe winner showed off her flawless legs in a flirtatious all-black ensemble.

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Aniston stopped to talk with ET’s Nischelle Turner where she opened up about getting the jitters while sharing scenes with the iconic Pretty Woman star.

When asked why she was felt intimidated by working with the Oscar winner, Aniston explained, "Because it's Julia Roberts! Oh my gosh!"

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Despite having known Roberts before co-starring in the Garry Marshall-directed ensemble comedy, Aniston explained that acting alongside someone you revere is totally different than just being friends with them.

"It's just a different thing when you get to work with them and then you're doing what you both do, [but] together," Aniston said. "I even flubbed in the first take and called her Julia!"

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If you don't believe her, Aniston's adorably embarrassing outtake is actually shown during a collection of bloopers at the end of the film.

Mother's Day was the first film Aniston worked on after tying the knot with Justin Theroux last August. Check out the video below for a behind-the-scenes look at Aniston's role in the rom com, which hits theaters April 29.

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