Serena Williams is on Vanity Fair's cover, says she 'accidentally' learned she was pregnant.

Tennis superstar Serena Williams is on the cover of Vanity Fair in an image that speaks volumes to her strength—and her beauty.

The 23-time Grand Slam winner is naked, holding her pregnant belly, her hair flowing behind her shoulders, her face in profile.

The pose is a throwback to the famed Demi Moore cover of the early 90s—except this time the overwhelming feeling is: power.

In the accompanying interview, Williams, 35, recalls the moment she found out that she and fiance, Alexis Ohanian, 34, the co-founder of Reddit, were expecting a baby.

“I did a double take and my heart dropped. Like literally it dropped,” she told Vanity Fair. The news came only days before she was set to compete in—no, win—the Australian Open.

Williams was in Melbourne last January, preparing for the Australian Open, when she felt her body was different. She was missing backhands, she had thrown up unexpectedly, and her breasts were enlarged.

Williams guessed it might be hormonal but pregnancy never entered her mind. It was her friend Jessica Steindorff who convinced her to take a test.

Williams replied: “I’ll take it just because a) to prove you wrong, and b) because it’s fun, whatever. It’s like a joke. Why not?”

Williams peed on the stick and quickly forgot about it. She and Steindorff were preparing to attend an event sponsored by the lingerie company Berlei, known for its sports bras and for which Williams is a spokesperson. Ohanian, meanwhile, was in the U.S., preparing to fly to Australia to watch the tournament the following week.

“I put [the test] down. I went back to finishing hair and makeup, was laughing, talking. I was getting the styling done,” Williams said.

“An hour and a half later, I went back to the bathroom to get dressed and was like, ‘Oh yeah, that test.'”

It was positive.

“Oh my God, this can’t be—I’ve got to play a tournament,” Williams said at the time. “How am I going to play the Australian Open? I had planned on winning Wimbledon this year.”

It took six further tests to convince Williams her pregnancy was real.

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She called her fiance to Australia early but didn’t tell him why.

At the airport, she handed Ohanian a paper bag with the six positive tests inside. He was shocked but there were more important things to consider: The Australian Open was imminent and Williams wasn’t only expected to play, she wanted to win.

The pair consulted a doctor to make sure that competing wouldn’t harm the baby—then Williams went on to win seven matches in straight sets, taking the title with an eight-week baby growing inside.

Williams and Ohanian plan to be married in the fall after their baby arrives.

The tennis legend, who has earned $84,463,131 in career prize money alone, is determined to be back on the courts by January next year.

“I don’t think my story is over yet,” she told Vanity Fair.