"From the world's oldest number one to the world's youngest number one."

Lauren Porter
Apr, 24, 2017

Mom-to-be Serena Williams is gearing up for motherhood and pregnancy already looks good on her.

On Instagram, the tennis star has made her first public acknowledgement of the news that she is expecting her first child. 

While sitting beachside, wearing a black bikini and a natural face sans makeup, Williams shared a sweet love letter to her growing baby bump. 

"My Dearest Baby, You gave me the strength I didn't know I had," she wrote in a caption. "You taught me the true meaning of serenity and peace. I can't wait to meet you. 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. On @alexisohanian bday. from the world's oldest number one to the world's youngest number one. -Your Mommy."

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Williams shared a Snapchat photo last week with the caption "20 weeks" and nearly broke the internet with the news. After the picture was deleted, her rep confirmed that the 35-year-old is indeed expecting. 

At the five-month mark in her pregnancy, the announcement meant she was pregnant when she won her 23rd Grand Slam back in January before pulling out of two matches in March citing a knee injury. 

It looks as if 2017 is shaping up to be a good year for the champ who is taking a well-deserved break from the courts. Just before the new year, Williams became engaged to Reddit cofounder Alexis Ohanian. The couple hasn't announced a wedding day but they'll welcome their bundle of joy in the fall.