Tennis pro Serena Williams is officially a new mom!

The sports star gave birth to a baby girl this week, her coach confirmed on Twitter.

Tweeting to Williams and her fiancè, Reddit co-founder Alexis Ohanian, the athlete's coach, Patrick Mouratoglou, gushed, "Congratulations...for your baby girl. I am so happy for you and I feel your emotion. Recover well & enjoy without limitation!"

According to CNN, Williams' sister Venus also confirmed the happy news during an interview before her U.S. Open match on Friday (September 1), sharing about being a new aunt, "Obviously I'm super excited, words can't describe!"

Williams announced her pregnancy back in April on Snapchat. Soon after, the then-mom to be penned a sweet message to her baby on Instagram.

"My Dearest Baby, You gave me the strength I didn’t know I had. You taught me the true meaning of serenity and peace. I can’t wait to meet you," she wrote. "I can’t wait for you to join the players box next year. But most importantly, I am so happy to share being number one in the world with you…. once again today…from the world’s oldest number one to the world’s youngest number one."

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