Will Smith: Venus, Serena 'cried all the way through' film 'King Richard'

Will Smith elicited an emotional reaction from Venus and Serena Williams with his portrayal of their father in "King Richard."

Appearing on Tuesday's episode of "The Tonight Show Starring Jimmy Fallon," Smith explained how the Williams sisters wouldn't commit to attaching their names to his new film as executive producers until they saw it.

"So, then I get the call that Venus and Serena are walking into the theater to see the film, and it's the worst two hours ever. The worst two hours," Smith said. "You know, 'cause you spent so much time creating these things, and there's literally only one audience. I did it with Muhammad Ali and then with 'Pursuit of Happiness' and 'Concussion,' with people that were all alive.

"It's the only audience, and you just hope to God - you've spent a year to tell this story, and you hope that they like it. And Venus and Serena cried all the way through, and they loved it."

"King Richard" tells the story of Richard Williams and how he helped turn his daughters into tennis superstars. It stars Smith in the title role with Saniyya Sidney and Demi Singleton portraying Venus and Serena, respectively.

"We all feel like we have a picture of Richard Williams, and it's the classic overbearing father hammering his children. But in sitting with Venus and Serena and their sisters and their mother, it was completely the opposite," Smith said. "He was a loving, caring, doting father."