World number two Serena Williams is pregnant and due in the autumn, her representative has confirmed.
The 35-year-old earlier posted a picture of herself on Snapchat posing in a mirror with the message: "20 weeks" before deleting the post.
The American, who won an Open-era record 23rd Grand Slam in Australia in January, will miss the rest of the season.
This includes three Grand Slams - the French Open, Wimbledon and US Open.
Williams, who will return to world number one next week, would be eligible to retain her ranking under the WTA special ranking rule if she is ready to play her first tournament within 12 months of giving birth.
US Open Tennis responded to Williams' message by saying: "Serena Williams will have a new pride and joy to hug and call her own soon! Congratulations on the exciting baby announcement!"
Would it be a 24th Grand Slam in France 2018?
BBC tennis correspondent Russell Fuller:
We are very unlikely to see Serena compete in another Grand Slam before the French Open of 2018. That event will take place four months before her 37th birthday - but do not write off a woman who will return to world number one on Monday.
Victoria Azarenka is a useful guide. Even though she is eight years younger, Azarenka gave birth to her first child in December, returned to serious training in March and is targeting the WTA event in Stanford at the end of July for her return to the WTA Tour.
