SANTA MONICA, California — For an actress who has starred in a string of comedic flicks over the last few years, pop ingenue Mandy Moore isn't too proud to admit that in her new film "License to Wed" she's ... well, she's actually not that funny.

"I would not consider myself a terribly funny person at all, that's why I feel lucky that a lot of the comedy in this movie doesn't rest on myself or my character," the 22-year-old singer/actress admitted. "Leave that up to the pros."

(Check out photos from the set of "License to Wed.") In her defense, Moore could do a lot worse than deferring to pros Robin Williams and John Krasinski (NBC's "The Office"), her two co-stars in "License to Wed." "Luckily, I just get to sit back and laugh — or rather, not laugh — on camera," Moore said. "That's been the real test on this film. I found that I tend to break a lot, working with the two of them."

The temptation to break character was a constant urge, Moore revealed, with a script she described as full of "chaos and mayhem." "I play Sadie Jones, who is a part of a couple that's getting married," Moore explained. "My one stipulation is that [Krasinski and I] get married in this certain church that I grew up going to, and we have to be married by this certain reverend [Williams]. And the only way he'll marry us is by putting us through this marriage course in three weeks, so we can be prepped."

For Krasinski, getting a chance to work with Williams was a lifelong dream come true, and he cited the comic's work as having a large impact on his own career. "Robin Williams influenced my comedic abilities way before I ever did this movie. I wrote him a letter when I was 12 saying he was my favorite comedian, and he wrote back, gave me a signed photograph from 'Good Morning, Vietnam,' " Krasinski recalled. "He has a really great sense of play, which is a word you hear a lot if you're an actor. It's not about one specific joke, it's about an energy and an enthusiasm and making each scene the best it can be. And he does it better than anybody."

Krasinski, best known to audiences as Jim Halpert on "The Office," said that Williams reminds him of his sitcom co-star Steve Carell, which is "funny because Steve Carell's character's number-one idol is Robin Williams for his improv skills.

"Both are unbelievably funny, and as people they are incredibly down to earth and giving," he continued. "I think it's teaching me what people who are incredibly successful have in common — they have the ability to be much more than an actor or a performer."

So did Krasinski, like Moore, have the constant urge to crack up during filming? Only when Williams led the way.

"We were doing a scene where some prop comedy came into play. I was breaking peanuts to show how tense I was. They might as well have been exploding peanuts," Krasinski explained. "Robin Williams, of all people, starts laughing, and that gives me the go ahead to start laughing. If he goes there, we'll all go there, no matter what mood we're in. It's a great life lesson."

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