Serena Williams spotted one major detail hidden in Zendaya's Challengers film: "She knows, she's the best of the best"

Following the release of her new movie, Challengers, Hollywood actress Zendaya disclosed that WTA great Serena Williams picked out a detail which was unnoticed by almost every other viewer.

Challengers is a romantic comedy that features Zendaya as the protagonist, a former tennis player who tries to revitalize her husband's tennis career. The film also stars Josh O’Connor and Mike Faist, and is set to hit theaters on Friday.

In an interview with Entertainment Tonight, the actress spoke about watching the premier with Williams. Zendaya revealed she had never touched a tennis ball before taking on the role. Furthermore, she admitted all she knew about tennis were the Williams sisters and “probably Roger Federer.”

However, Zendaya stated Williams approved of her performance in the movie. Additionally, the 23-time Grand Slam champion noticed a major detail that seemed to elude most viewers.

“She was like, ’I know there definitely weren’t real [tennis] balls,’” said Zendaya. “She knows. She’s the best of the best.”