Cue the confetti!
In Wednesday's Snapchat story, the photo before Williams' exciting selfie includes what looks like a baby mobile, with an adorable smiling sun. Kelly Bush Novak, Williams' spokesperson, told Refinery29 she was "happy to confirm Serena is expecting a baby this fall."
Eagle-eyed fans on Twitter, including BuzzFeed's Jarrett Wieselman, were the first to spot the news.
Williams and her fiancé, Reddit cofounder Alexis Ohanian, have been engaged since December. Before announcing their engagement, the pair had been dating since 2015. Williams announced the news with an adorable Reddit post on the subreddit r/isaidyes. (Naturally, Williams is a "verified GOAT" on Reddit.)
The happy couple recently shared an adorable photo from a romantic trip to the beach. It's clear this baby will be joining one happy, loving family.
Fans were quick to congratulate Williams and Ohanian on the happy news (and to note how radiant Williams looks in the snap). Others noted that between Williams, Ciara, and Beyoncé, it's a pretty great time for celebrity pregnancies.
And one Twitter user pointed out that if Williams is 20 weeks pregnant, that means she was pregnant when she won the Australian Open in January, marking her 23rd Grand Slam title. Yep, that definitely makes her the GOAT.
This story has been updated to include a comment from a rep for Williams.