Tennis superstar Serena Williams gave birth to a 6-pound, 13-ounce baby girl on Friday, according to ESPN.

Moments before her match at the U.S. Open, Venus was asked about becoming an aunt.

"Obviously I'm super excited. Words can't describe," she told ESPN.

Serena announced in April that she was pregnant, posting a selfie on Snapchat with the caption “20 weeks” and later confirming that she and fiancé Alexis Ohanian were expecting their first child.

She learned she was pregnant just days before the Australian Open began. For her 23rd Grand Slam singles title, Serena beat big sister Venus in the final.

In true Serena fashion, she has been adamant she’ll return to the tour after having the baby.

Her coach, Patrick Mouratoglou, said in an interview recently that the plan is for Williams, barring any complications, to start training in November.

“The goal is to be ready for the Australian Open and then we’ll see,” said Mouratoglou, of Williams’ desire to defend her title. “If she’s ready, she’ll compete. If not, we’ll delay the comeback. I don’t think she should compete if she’s not really ready.”