The tennis champ says she and her fiancé Alexis Ohanian are waiting to meet their little one to learn the baby's sex.
Before you break out the pink balloons for Serena's unborn child, you may want to hold off on that.
While fans thought Venus Williams had spilled the beans and revealed that her little sister is having a girl, Serena has set the record straight so there's no confusion.
During an interview with Eurosport on Wednesday, Venus excitedly refered to her baby sister's offspring was a "she." The expectant mother took to Instagram on Thursday morning to clarify comments her sister made about the gender of her baby.
"I think the surprise of knowing what you are going to have on that very special day you give birth is prob the best surprise you can ever have!," the 35-year-old wrote.
"So to clarify what Venus said, I am always joking with my sisters to see what favors I can get them to do for me next. If I want something from one of my sisters I say baby Venus baby Lyn, or Baby Isha needs it. I did not grow up with any brothers, only sisters and we all say "she" more than "he." Unless I'm joking with my Dad or Alexis and I'm trying to con something out of them too. Hey I'm the youngest of 5 I've always tricked all of them what can I say!"
And there you have it.