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Fatherhood usually brings out the softer side of a man -- but not for Hayden Panettiere's fiance, Wladimir Klitschko.

In fact, "being a father has made him even more aggressive and dangerous," says the "Nashville" actress who gave birth to her first child with the Ukranian boxer, daughter Kaya, in December 2014.

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The new mom dished on how fatherhood has changed her longtime partner during an appearance on "Live! With Kelly and Michael" on Wednesday, April 22, 2015, acknowledging that her off-and-on love of more than five years -- who's set to face Bryan Jennings during the World Heavyweight Championship in New York City on Saturday, April 26 -- has become a more determined fighter now that he's fighting for someone.

"He's Papa Bear," she gushed.

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Hayden also opened up about how sharing a child has changed her relationship with her fiance: "You have much more of a connection," she told co-hosts Kelly Ripa and Michael Strahan. "When you're with somebody, I feel like it's great when you have your own life, they have their own life, and you meet gracefully in between. But then the longer you know them, the more you're attached to them, and then something that bonds you is a child. When you have a child together, there's nothing that connects you like that forever -- for better or for worse!"

And Wladimir isn't the only one who's been affected by parenthood! When Michael Strahan asked the "Heroes" alum how her life is different since her daughter's birth, Hayden shot back: "How's it not?"

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"You kind of lose yourself in the most out of body way, but also the best way," she added. "It's just such a great experience being a mom."

As for her impressive post-baby body: "It's all about the undergarments," the petite blond demurred when Kelly Ripa complemented her on her slender appearance.