And baby makes four! Serena Williams and her husband, Alexis Ohanian, took to social media on Tuesday to announce that they welcomed their second child, daughter Adira River Ohanian.

The couple, who tied the knot in 2017, are also parents to Olympia, 5. 

In a sweet TikTok video set to Bazzi's 2018 track, "Beautiful," Williams and Ohanian can be seen sitting at a table -- laptop and coffee mug also in view -- embracing each other before Olympia jumps into her mom's arms to join them.

After giving Olympia a kiss on the forehead, Williams turns to Ohanian and appears to say, "I'll be right back."

Williams, dressed in an oversized pink hoodie and sneakers, then walks back with her new baby girl. Ohanian closes his laptop and gives his wife a kiss while gently placing his hand on the back of the baby's head.

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A post shared by Serena Williams (@serenawilliams)

Olympia then sweetly gives her baby sister, who is tightly but comfortably wrapped in a blanket, a kiss. The 1-minute video ends with Polaroid photos of the family's special moment. The proud mother captioned the video, "Welcome my beautiful angel."

Ohanian also shared the news on his Instagram page, sharing three photos of the new family of four. 

"Welcome, Adira River Ohanian," he began his caption, revealing the baby girl's name. "I'm grateful to report our house is teaming with love: a happy & healthy newborn girl and happy & healthy mama. Feeling grateful. @serenawilliams you've now given me another incomparable gift -- you're the GMOAT. Thanks to all the amazing medical staff who took care of my wife & our daughter 🙏 I'll never forget the moment I introduced @olympiaohanian to her baby sister."

@serena

Welcome my beautiful angel

♬ original sound - Serenawilliams

"'Your peace would have been like a river, your well-being like the waves of the sea,'" he concluded his post.

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A post shared by Alexis Ohanian Sr. (@alexisohanian)

Williams and Ohanian shared they were expecting their second child as they walked the carpet at the 2023 Met Gala. 

"Was so excited when Anna Wintour invited the 3 of us to the Met Gala," Williams captioned the photo of her showing off her baby bump in a black Gucci gown as she stood next to the Reddit founder.

Since her announcement, the tennis legend has been excitedly sharing her second pregnancy journey with her fans online, even posting the moment when she and Ohanian shared the news with their daughter that she was getting a promotion to big sister. 

"Remember how you've been praying for a little sister or brother? Well, we went to the doctor and it turns out I'm not getting fat. But I have a baby in my belly," Williams said, to which Olympia promptly asked excitedly. "Are you kidding me?!"

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A post shared by Serena Williams (@serenawilliams)

Prior to the release of the video, Williams explained why she and her husband kept their news from their daughter until they were ready to share it with the rest of the world.

"Olympia does not know right now that I am pregnant, so the big reveal will be at the Met and then before we leave, I'll tell Olympia," Williams explained in an Instagram video. "The reason I haven't told her is because she can't keep a secret!"

Before her announcement, Williams "stepped back" from her professional tennis career via an essay printed in Vogue, sharing that although she's not "officially retired," she is taking time to focus on her family.

In the essay, the 23-time Grand Slam winner detailed how she and Ohanian have been planning for more additions to their family. "In the last year, Alexis and I have been trying to have another child, and we recently got some information from my doctor that put my mind at ease and made me feel that whenever we're ready, we can add to our family," she shared. "I definitely don't want to be pregnant again as an athlete. I need to be two feet into tennis or two feet out."

After all, she experienced the hardship of doing both firsthand. "The way I see it, I should have had 30-plus grand slams. I had my chances after coming back from giving birth. I went from a C-section to a second pulmonary embolism to a grand slam final," Williams candidly recalled. "I played while breastfeeding. I played through postpartum depression. But I didn't get there. Shoulda, woulda, coulda. I didn't show up the way I should have or could have. But I showed up 23 times, and that's fine. Actually, it's extraordinary. But these days, if I have to choose between building my tennis résumé and building my family, I choose the latter."

As she pointed out in the piece, it's not a decision a man would have to face the same way. "If I were a guy," she said, "I wouldn't be writing this because I'd be out there playing and winning while my wife was doing the physical labour of expanding our family. Maybe I'd be more of a Tom Brady if I had that opportunity."

Although Williams admittedly struggled to simply "be" during her time off, it's safe to say she'll have more than enough to keep her occupied with baby number two at home.