She’s growing up! US Open star Serena Williams’ baby girl, Alexis Olympia, turns one

SHE’S in career-best form at the US Open and Serena Williams has another reason to celebrate … her baby daughter has turned one. 

Williams’ husband, tech entrepreneur Alexis Ohanian, posted an adorable tribute to the couple’s little girl, Alexis Olympia Ohanian Jr (known as Olympia), on her first birthday.

Williams, 36, however, does not celebrate birthdays due to her strict Jehovah’s Witness beliefs.

Reddit founder Ohanian posted a photo of the little tot captioned “adventure princess”, which has received more than 72,200 likes and 1,200 comments, according to Fox Sports.

But Williams recently explained at a news conference why she wouldn’t be celebrating her daughter’s first birthday, People reported.

“Olympia doesn’t celebrate birthdays,” Williams was quoted as saying.

“We’re Jehovah’s Witnesses, so we don’t do that.”

Some confused fans commented on Ohananian’s post asking why they weren’t marking her first birthday.

“I’m not a Witness, but I considered how made up it all is: the purpose of celebrating a birthday is to celebrate life with the people who love you (and to eat cake),” Ohanian responded to one fan.

“This baby is loved and will get to celebrate life with people who love her *plenty* of times, with plenty of parties (and eat cake — in moderation) throughout her life.”

Meantime, Williams brought Olympia with her to the US Open last week, outfitting the 11-month-old in a little dress that looked a lot like the Off White x Nike designs she’s been wearing on the court, New York Post reported.

The infant wore a white tank dress with an ombré pink, white and blue tulle overlay paired with white socks and cap-toed sneakers.

The 23-time Grand Slam champ has been sporting similar styles at the US Open, thanks to the “Queen” collection Off White’s Virgil Abloh designed for her.

During her matches on Wednesday and Thursday last week. Williams wore one-shouldered tutu dresses with full tulle skirts from the range — the first one black, the second lilac.

Both outfits feature Abloh’s signature Nike logo in quotation marks at the shoulder, as well as Williams’ name on the sleeve.