In the pantheon of romantic comedies, there's "Annie Hall" ... and then there's everything else. But don't take our word for it.

"['Annie Hall' is] the greatest romantic comedy ever made," Mandy Moore recently proclaimed.

We'll entertain no challenges for the mantle. Why? Because Moore said so. Or, more correctly, "Because I Said So," a new romantic comedy that teams the singer/actress with "Annie Hall" star Diane Keaton as a daughter-and-mother team who are both looking for love.

Moore said that working with the Oscar-winning master of the genre proved a challenge she was ready to embrace. "You have no choice but to raise your game with Diane Keaton, she is just that incredible," Moore said. She added: "It was fun as an actress to challenge myself, to get over that fear. She's on such a pedestal for me. To conquer and master that nervousness [was difficult]."

Released in 1977, "Annie Hall" remains the only straight-up comedy to win the Oscar for Best Picture in the past 50 years. According to Moore, that's a testament to how difficult romantic comedies are to make.

"These are the types of movies that I gravitate toward in real life. I love seeing a good romantic comedy or relationship comedy," Moore said. "[But] it's hard to make these movies good. There are so many points where you could fail and lose your way. It's a difficult genre to master."

Perhaps the key, Keaton mused, could be found not in silly premises or oddball pairings (as has been the recent trend), but in the simple beauty of honest performances. "The thing about romantic comedies is that you just have to rely a lot on performance," the 61-year-old actress said. "It [doesn't have] the amazing aspects of real drama or thrillers. It's more difficult than other comic genres. It's more delicate."

As Moore's love interest in the film, co-star Gabriel Macht ("The Good Shepherd") had plenty of opportunities to ham it up. But it was Keaton's perspective, he said, that kept his performance grounded.

"I just wanted to play [the role] truthful. I'm just trying to tell a story," Macht said. "I'm never playing for laughs, so I'm not playing for the comedy. I'm never playing to be cool and sexy and hot, so I'm not playing for the romance. I'm just playing a guy who's falling in love with a girl."

While it's a philosophy that has served her well in nearly a dozen romantic comedies, and earned her two Oscar nominations (including one win) in the genre, Keaton thinks it may be time to pass the torch. "Mainly, I don't think people really are really interested in watching [me in romantic comedies]," she sighed. "You know what I mean? 'Gee, I can't wait to see a romance with Diane Keaton. Pencil me in, I'll be there!' I don't think that's part of the deal."

If it is time to move on, Keaton said the future looks bright for Mandy Moore. "I think she has a huge future as an actress. I think she's got everything you need and more," Keaton said. "I think she's going to have an amazing career and her work [will] just get better and better."

Check out everything we've got on "Because I Said So."

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