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

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

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

Serena Williams had the baby in West Palm Beach, Fla., ESPN reported.

“I’m so thrilled for her, what a role model she’s going to be for that daughter," ESPN commentator Chris Evert said during Friday’s afternoon broadcast of the U.S. Open. "I told Serena this, it’s a love you’ve never felt before and I know she’s probably experiencing that right now.”

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.

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

Her coach, Patrick Mouratoglou, tweeted his congratulations to Williams and Ohanian. "I wish you a speedy recovery... we have a lot of work ahead of us," he wrote to Williams.

Mouratoglou said in an interview with USA TODAY Sports recently that the plan is for Williams, barring any complications, to start training in November.

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“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.”