Kate Hudson and Anne Hathaway normally play princesses, heroines and business women at the top of their game. But for their new movie “Bride Wars,” which premieres Jan. 9, Hudson and Hathaway explored their darker sides to portray cutthroat Bridezillas, willing to do anything to save their wedding.

Hudson and Hathaway play the characters Liv and Emma, best friends who’ve planned their weddings since they were little girls. At 26, both finally receive rings and can start planning the ultimate wedding. But their perfect day just couldn’t be without the ceremony taking place at the Plaza Hotel. Through a top-notch wedding planner, they’re able to secure two dates at the Plaza during the same month. Everything seems to be going as planned, until they receive the news that a clerical error has occurred, and now they are to be married on the same day. They can’t decide who should fairly get the wedding date, so an all-out bridal war ensues and it’s every bride for herself.

“This script was so great in providing a logical, emotional back story for the characters to explain why they go off the deep end the way that they do, and why this war was, in some ways, a long time coming,” Hathaway said in a conference call. “So there was a certain freedom that the script gave us, because it was grounded in truth.”

Besides playing one of the main characters, Hudson was also a producer for “Bride Wars.” She said she felt that this was a “nice one out the bat for me to be able to get going with” because it was a high concept comedy.

Hathaway said that producing was something she was theoretically interested in, but probably wouldn’t act in the movie if she produced it.

This was also the first movie that Hudson and Hathaway starred in together. Hathaway said she was a huge Kate Hudson fan prior to working with her and that she’s learned from Hudson the ability to have fun at work.

“Kate does something which is so incredibly rare in an actress, which is that she’s able to find the balance between being professional and having fun,” Hathaway said. “I can get lost and mired down in the professional side of things and Kate – without sacrificing any of the work, without taking it any less seriously than anyone else – manages to just bring a sense of fun to absolutely everything.”

Hudson and Hathaway had a lot of fun filming the movie because in a bridal war there were no rules. Liv and Emma pulled every underhanded trick possible. Hair was dyed blue and skin was dyed orange. Not even the wedding dresses were safe.

Hathaway thought that the meanest thing Emma did to Liv was causing her to unknowingly gain weight.

“That’s low,” Hathaway said. “That’s something that girls don’t do to each other. I know how hard I have to work to lose that last five pounds, so to kind of mess with that I think is wrong.”

Hudson’s favorite mean act was Liv sabotaging Emma at the tanning salon. Hudson said she enjoyed wearing and playing Liv’s version of a disguise. For every take, she played a different character.

“As a kid, sketch comedy and improv was really what I liked to do, and where I really love to get down and dirty,” Hudson said in a conference call. “For this movie and that one particular scene, I was literally a Russian girl. I came down with some weird version of an Eastern European girl. I did a southern belle.”

Hudson also said she hopes all of the characters who didn’t make the cut for that scene will be on the DVD.

To play women capable of performing such devious acts, Hudson and Hathaway had to channel their inner Bridezillas. Hathaway said she just used her imagination and experience.

“We’re human beings so I think we understand what it’s like to be jealous, competitive or catty,” she said. “Maybe we don’t indulge in those feelings or try not to live in that world, but I think those urges are understandable.”

Hudson used the experience of her own wedding and her friends’ weddings for inspiration. She said she understood the stress that Liv and Emma were going through, and she also understands the emotional nature of women and their tendency to get a little carried away.

“With this movie, it was so fun to be able to make fun of ourselves,” Hudson said. “I think girls get crazy, but we can also laugh at ourselves really well. We don’t get the opportunity to do that very often in movies. So for me, it just felt like you can tap into all of those things you’ve learned as a girl throughout the years.”

Although Hudson and Hathaway empathize with their characters, they agreed that Liv and Emma went overboard in “Bride Wars.”

Hudson said she’s similar to Liv because she’s very driven. But Hudson does have her stopping points and doesn’t go to any lengths to get what she wants, like Liv does.

Hathaway relates to Emma because she’s happy being the peacekeeper. However, Hathaway said she has a limit to what she will put up with.

“Emma is much happier keeping the peace than causing a ruckus,” Hathaway said. “I could definitely relate to that, but I’ll hold my tongue a lot earlier than Emma does. I think that I’m happier sort of stepping back, but I also don’t let people walk all over me.”

The part of Emma and Liv that Hudson and Hathaway and countless other women can relate to is dreaming and fantasizing of the perfect wedding as a little girl.

Hudson’s parents, who weren’t married, ingrained in her that a couple didn’t need to sign a piece of paper saying that they loved each other or that they were a family. But when she met Chris Robinson, her ex-husband, she had a change of heart.

“For me it was more about who was going to be the guy that I would spend the rest of my life with,” Hudson said. “When I met Chris, I got really excited and was like ‘I’m getting married!’ I was very excited about possibly calling up Vera Wang and seeing what she could do for me.”

Hathaway’s fantasy wedding is shared by many women and girls.

“I always fantasize that Leonardo DiCaprio and I will meet at some point, and he’ll just see me walking down the street and fall in love with me and that’ll be that,” Hathaway joked. “It was kind of a vague notion, and I just assumed that Leo and I would have a glorious wedding. It doesn’t look like that’s going to happen, however. So, my fantasies have taken a left turn.”

Hathaway then said she’s never actually planned her wedding. Like Hudson, she’s always focused more on the guys.

Besides Hudson and Hathaway, this comedy is full of top-quality actors and actresses like Bryan Greenberg, Steve Howey, Chris Pratt, Candice Bergen and Kristen Johnston. It’s directed by Gary Winick, who also directed “13 Going on 30.”

“When it [Bride Wars] was done, I was so excited,” Hudson said. “I was like, ‘I just can’t wait to see it with my girlfriends.’ It’s that movie you want to see with your best girl friends, and that made me so excited about it.”