Transcript for Football's Unbeatable Father Daughter Team

America strong. He's an NFL star, but to his 4-year-old daughter, he's just dad. Fights her own enemy. And before he takes the field tonight in front of millions, something you won't see. The tea party, pink cups and all, because that little girl comes first. She is finally there. Right into the arms of her father. Hi, daddy. Reporter: Devon still, his daughter Leah. Long before he takes the field tonight, he's fighting another enemy. Right beside his daughter. 4-year-old Leah was diagnosed with cancer in June and so many people across this country have seen this, on her way to treatment, a remarkable moment between a father and daughter. I'm ready for today. You ready for today? You ready to get this cancer up out you? Let's do it! Fist bump! Reporter: After the diagnosis, doctors weren't sure she would survive it. The six-hour surgery, the tumor removed. And now chemo, but she is coming through. And her dad inspiring her every step of the way. Listen to what he told her about her hair. You are going to be just like this. And we're going to look just like twins. Daddy, I'm on a plane! Reporter: Overnight, Leah strong enough to make that flight to Cincinnati, where the Bengals have donated more than $1 million to pediatric cancer research. And today, that proud dad and his daughter telling me about their tea party. The NFL star, who knows pink cups and imaginary tea comes first. I saw you had a very important tea party with daddy before the big game. Yes. Reporter: Yeah. That's a good dad on the big game day, to take a break for a tea party. I don't think I'm doing nothing extra. I'm doing what every father would do. Reporter: What made you think to do that fist bump in the car? She was a little nervous on her way to the hospital that morning before the surgery. And I know she loves the camera, and every time I bring out the camera, she always puts a smile on her face. Reporter: Leah, is that true? Do you love the camera? Yeah. And since she loves the camera, we thought we'd give her another chance at that fist bump. This time, in front of millions watching all over America tonight. Ready? A dad, ready for the big game tonight, and ready to keep fighting for his daughter. What a face. And a fist bump for Leah tonight. Hope to see you here tomorrow night.

This transcript has been automatically generated and may not be 100% accurate.