Her sister Venus had hinted the unborn tot was to be a girl at the French open on Wednesday.
But after a flurry of questions from confused fans, Serena Williams has now taken to social media to confirm that she does not know the gender of her baby.
The pregnant tennis ace, 35, shared a message on Instagram which explained how the Williams clan all use the word ‘she’ more than ‘he’, as they grew up with sisters – and that finding out on the day will be the ‘best surprise’ of her life.
The athlete, who is expecting her first child with Alexis Ohanian, revealed she is keeping the gender a surprise for the ‘special’ day they welcome the tot.
She began: ‘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!’