Serena Williams is publishing her first children's book — about her daughter's Insta-famous doll

Serena Williams is already one of the best tennis players, and overall athletes, of all time, with 23 Grand Slam titles and four Olympic gold medals. Now, she's looking to expand on her success off the court — this time, by writing a children's book. 

Williams announced the news on her Instagram on Thursday, saying that the book will be about her toddler daughter Alexis Olympia Ohanian's beloved doll Qai Qai, which Williams created herself. 

"Since realizing @RealQaiQai's ability to spread joy to our own family and also millions of others around the world, we've wanted to tell her story in every way possible," Williams said. "We are so proud to announce Qai Qai's first book, 'The Adventures of Qai Qai,' a story about the power of friendship and imagination." 

Williams created the Qai Qai doll in 2018. And the doll has been a trailblazer ever since, amassing more than 353,000 followers on Instagram — with her own coveted blue check — more than 25,000 followers on Twitter, and more than 3.2 million followers on TikTok. 

Her first posts were photos of Qai Qai lying on the floor and ground, but the doll quickly developed her own persona, with an animated version of Qai Qai  meeting "CBS Mornings" co-host Gayle King, traveling to Paris and even "camping" out at the 2019 Met Gala. 

In 2020, Williams made the doll available for others to purchase on Amazon, which describes Qai Qai as "smart, funny, relatable, and empowering" and says she "stands up for bossing up and chasing your dreams."

"Storytime is such an important pillar of our bedtime routine, like so many others around the world," Williams said in a statement. "Qai Qai is a special member of our family and we hope 'The Adventures of Qai Qai' will give others a new way to welcome Qai Qai into their home." 

The new book, according to its website, is about Qai Qai helping her best friend, Baby Girl, learn to believe in herself as she gets ready for her upcoming dance recital. 

"But what if I'm not good enough?" Baby Girl says in the book, according to an excerpt published on the book's preorder page. 

"Girl!" Qai Qai answered. "You're already good enough when you walk in the door! Come on, let me show you." 

The book, which will be released alongside entertainment technology company Invisible Universe and published by Feiwel and Friends, is illustrated by Yesenia Moises, an Afro Latina illustrator and designer. it will be published on September 27, 2022.