The top-ranked tennis player wasn't able to make it to Wimbledon this year, but don't worry, she's keeping plenty busy with drill practice.
Williams posted a video of herself putting in work on Monday morning, as her sister Venus, 37, held down the fort in London.
"Wimbledon got me like: Easy standing drills this morning. Go easy," Williams captioned a video of herself effortlessly flicking a ball around. (Well, she makes it look effortless, anyway. We're sure it's harder than it looks!)
A second photo shows Williams cradling her bump with one hand, racket in the other.
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The caption reads, "Sorry, White. Average Joes for life! And that goes for both of us." It's a response to a tweet from actor Ben Stiller last week, in which Stiller, 51, challenged Williams in costume as "Dodgeball" character White Goodman. It appears Williams will participate in a charity game for The Stiller Foundation, which provides educational opportunities for children around the world.
"Hey Serena! Now that you're the first woman to win a Grand Slam title while pregnant, let me impregnate you ... with this thought," Stiller said in a video. "It's time we co-mingle our forces. You dominate the tennis world, I dominate the dodgeball world. Globo Gym or Average Joes? Pick a side!"
It looks like Williams has chosen. (And so has her unborn doubles partner).
Now that's one heck of a backhand! But hey, it's for a good cause.