Tennis star Naomi Osaka announced Wednesday that she is pregnant with her first child and likely to be out of the sport for the entirety of 2023.

Osaka tweeted a statement and a photo of an ultrasound, and she declared that she would be back for the Australian Open in January 2024:

The 25-year-old is a Californian and represents Japan on the WTA. She spent 25 weeks as the No. 1 player in the world, and is a four-time Grand Slam champion, having won the Aussie Open twice and the U.S. Open twice.

Per CNN's Amy Woodyatt, Osaka's recent social media activity had led to speculation about her not participating in the 2023 Australian Open despite being on the entry list.

Woodyatt noted that Osaka reposted an image of herself at a pilates studio in the United States last week on Instagram, and she posted photos of herself and rapper Cordae—her boyfriend since 2019—in Paris on Dec. 28.

Although Osaka was among the top women's players in the world from 2018 to 2021, winning one Grand Slam title in each of those four years, she has struggled with mental health challenges and injuries since then.

After winning the 2021 Australian Open, Osaka refused to speak to reporters at the 2021 French Open and decided to withdraw from the tournament. She then took some time off from tennis and did not enter Wimbledon 2021.

Last year, Osaka dealt with numerous injuries, and did not make it past the third round at any of the three Grand Slam tournaments she entered.

Osaka also failed to win a tournament of any kind in 2022 with her best performance being a loss to Iga Świątek in the Miami Open final.

Given her lack of success last season, Osaka has dropped to No. 47 in the WTA rankings, and she figures to drop out of the rankings completely during her time away.

While returning to an elite level of play after giving birth won't necessarily be easy, it is far from unprecedented in the world of women's tennis.

Margaret Court, Evonne Goolagong and Kim Clijsters all won Grand Slam titles as mothers, and Serena Williams won the 2017 Australian Open while she was eight or nine weeks pregnant with her daughter.