Will Smith says Venus and Serena Williams insisted on seeing 'King Richard' before putting their names to it, and the screening was the 'worst 2 hours' of his life

• Will Smith described showing Venus and Serena Williams "King Richard" for the first time.

• The screening was "the worst two hours of my life," he said.

• Smith plays Richard Williams, the father of Venus and Serena Williams, in the biopic.

Will Smith appeared on "The Graham Norton Show" on Friday and described the uncomfortable experience of showing Venus and Serena Williams the biopic "King Richard," about them and their father.

Smith — who produced the film and starred as Richard Williams — said Venus and Serena Williams had agreed to act as executive producers on the film and aid the production but "wanted to see the movie before they decided if they would put their names to it."

According to preview quotes from the chat show sent to Insider, Smith called the screening for the Williams sisters "the worst two hours of my life," adding, "but they were a mess with tears, and they loved it."

Later, in reference to his previous work on "Ali," the biopic of the legendary boxer Muhammad Ali, Smith said: "I had made the mistake of watching 'Ali' for the first time while sitting behind Muhammad Ali, and midway through the movie he turned to his wife and said, 'Was I that crazy?'"