A photo shows Williams in a yellow swimsuit with a baby bump.
Tennis legend Serena Williams, who is arguably the greatest female tennis player to have played the sport, confirmed on Wednesday that she was pregnant and was expecting her first baby this year.
She pulled out of the recent tournaments in Indian Wells and Miami citing a knee injury but was scheduled to play at the Madrid Open next month.
With 24, Court has one more Grand Slam singles title to her name than Williams (though only 11 of those were won during the Open era).
Williams, who is 5 feet 9 inches (1.75 metres) and weighed 155 pounds (70 kg) according to her tennis association profile, won a 23rd Grand Slam tournament title at the Australian Open in January.
The 35-year-old expectant mom will not be back on the tennis circuit for the rest of the year.
With Williams and her representatives now being tight-lipped, however, no one is quite sure.More news: Aviva PLC (LON:AV) Issued With 'Sell' Rating At Berenberg Bank
"The official Twitter account for US Open Tennis also announced the news, writing, ".@serenawilliams will have a new pride & joy to hug and call her own soon!
She has bestrode tennis like a colossus and now it looks like she may have won the Australian Open, while in the early stages of pregnancy.
Just days ago, she implied on Instagram that she was not pregnant while promoting her friend and former Destiny's Child singer Kelly Rowland's new book for expecting mothers. And did not drop ONE SET. Twice Wimbledon champion Petra Kvitova is still recovering from the effects of a awful assault at her home, which damaged her hand.
Other women have left the tour to have children and returned at a high level, though none has done so at Williams' age.
She has won two of the last three grand slam titles, and 10 of 19 since teaming up with her coach Patrick Mouratoglou in 2012.
Five-times Grand Slam victor Maria Sharapova, who returns to competition next week after a 15-month doping ban, could also benefit if she rediscovers her top form.