Serena Williams is a world-class tennis player, but she has a secret that she shared during her latest appearance on "The Ellen DeGeneres Show," scheduled to air on May 2.

In a sneak peek of the episode posted on YouTube, Williams admitted to having signed up her 4-year-old daughter Olympia, for tennis classes anonymously, according to ET Canda.

The nearly 8-minute clip started with the audience being shown a couple of photos of the mother-daughter duo where they both wear matching outfits, and Williams described her daughter as her "twin."

Then, DeGeneres asked Williams, "how is she at tennis?" This prompted Williams to pause before admitting that while Olympia was not completely bad, other 4-year-olds might take her out.

“Her ambition is playing princess games. She loves princess games and the more we can play anything with princesses, that's her whole life," continued Williams, of Olympia.

“You enrolled her in tennis classes with a coach but you did not tell the coach that you were the mother?” asks DeGeneres.

Serena Williams is still chasing a record-equalling 24th major
Serena Williams is still chasing a record-equalling 24th major AFP / Christophe ARCHAMBAULT

"So, this is such a funny story, because I don’t have the patience to teach tennis. It's so weird because I don't really like to play tennis with people who don't know how to play tennis well. It drives me nuts,” replied Williams.

"I don't have the patience for it, so I signed her up for a class, a private teacher, and so she came in, and I didn't want to tell her," the 40-year-old admitted. But she did share a story on her Instagram about her daughter's tennis classes, which could have led the teacher to discover Williams' secret identity, she revealed.

The athlete and businesswoman then engaged in conversation about the acclaimed movie about her family, “King Richard.” She also spoke about how she felt while watching her friend Beyoncé perform the Oscar-nominated song from the soundtrack in the tennis star’s hometown of Compton.