Katherine Heigl faces off with '300' hunk Gerard Butler in the new comedy 'The Ugly Truth,' in theaters Friday, and the "Grey's Anatomy" star waxes poetic to ET's own Mark Steines about her sexy co-star, how men are still from Mars and women are still from Venus -- and will they ever understand each other?

"No," she says flatly. "But I think there is hope that we can maybe come to some sort of middle ground. When you really love someone you will definitely make the sacrifice for certain things. I will compromise a little of my uptightness, and [my husband] Josh will compromise his golf."

In the movie, Katherine plays Abby, a high-strung and romantically challenged morning show producer whose search for Mr. Perfect has left her hopelessly single. When hardcore TV personality Mike Chadway (Butler) enters the picture, Abby is in for a rude awakening, as Mike pulls no punches -- on air and off -- about the ugly truth on what makes men and women tick. Will their immediate friction create sparks? Or will someone go down in flames?

"It's so funny because I seem to play a lot of these uptight chicks, and I think it says a lot about me, so I relate," jokes Katherine. "And no, I've never printed out someone's profile or done a background check when we're on a blind date, but I did absolutely have a checklist. It wasn't quite as detailed as Abby's, but I had a pretty specific idea of what I wanted, or what I thought I wanted."

As for her smoldering co-star, Katherine pulls no punches: "I've seen Gerry in a tux, and it's hot. He cleans up really well. He's a man's man, and that's what makes him so appealing," she says with a glint in her eye. "We all talk about how we're missing the Cary Grants and those movie stars of old that were just these sexy, charismatic men, and I really feel like Gerry is filling that missing thing right now."

As for her new, brunette locks, she explains, "[My "Grey's Anatomy" character] Izzy's been blonde for five years; I can't mess with that. But she's bald now -- she's wearing a scarf. I can do whatever I want. So I shook it up."

Watch ET for more with Katherine!

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