Serena Williams debuts baby bump, poses with fiance at Met Gala

NEW YORK, NY - MAY 01:  Serena Williams (L) and Alexis Ohanian attend the "Rei Kawakubo/Comme des Garcons: Art Of The In-Between" Costume Institute Gala at Metropolitan Museum of Art on May 1, 2017 in New York City.  (Photo by Neilson Barnard/Getty Images)

Credit: Neilson Barnard

Credit: Neilson Barnard

NEW YORK, NY - MAY 01: Serena Williams (L) and Alexis Ohanian attend the "Rei Kawakubo/Comme des Garcons: Art Of The In-Between" Costume Institute Gala at Metropolitan Museum of Art on May 1, 2017 in New York City. (Photo by Neilson Barnard/Getty Images)

Tennis great Serena Williams and her fiance, Reddit co-founder Alexis Ohanian, made their red carpet debut -- along with Williams' baby bump -- at the 2017 Met Gala on Monday night in New York.

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Williams confirmed her pregnancy after speculation emerged when she accidentally posted a Snapchat of herself with a caption that said she was 20 weeks pregnant.

Posing in an emerald green Versace gown and a slicked back bob, Williams beamed as she stood next to Ohanian, according to Entertainment Tonight. Her left ring finger had an impressive-sized engagement ring.

On April 24, Williams celebrated her No. 1 tennis player ranking with an open letter to her unborn child.

"You gave me the strength I didn't know I had," Williams wrote in the Instagram post. "You taught me the true meaning of serenity and peace. I can't wait to meet you."

Williams and were also featured in Humans of New York. The photography series creator Brandon Stanton posts images in his usual style -- a photo with a caption from a party in the image -- every year in Vogue magazine after the gala.

“She has the biggest heart,” Ohanian, who got engaged to Williams in December, told Stanton. “Everyone sees her success as an athlete, but all of that is layered on the size of her heart. She gives 100 percent of herself to everything she does: as a friend, as a lover, and soon, as a mother.”