A spokeswoman for Serena Williams says the tennis star is pregnant.

Kelly Bush Novak wrote in an email to The Associated Press on Wednesday: "I'm happy to confirm Serena is expecting a baby this Fall."

Earlier in the day, Williams posted a photo of herself on the social media site Snapchat with the caption "20 weeks."

The 35-year-old Williams won her 23rd Grand Slam singles title at the Australian Open in January - a little less than 12 weeks ago - and has not competed since, citing a knee injury when withdrawing from tournaments at Indian Wells, California, and Key Biscayne, Florida.

She announced in late December that she was engaged to Reddit co-founder Alexis Ohanian.

Serena Williams is expecting!

The GOAT took to Snapchat to announce that she is 20 weeks pregnant. (via @serenawilliams/Snapchat) pic.twitter.com/7O9ub0VWVK

— espnW (@espnW) April 19, 2017

My only regret is not pointing my toe sorry coach Garry ??

A post shared by Serena Williams (@serenawilliams) on Apr 17, 2017 at 6:29am PDT