Serena Williams is pregnant again. The 23-time Grand Slam champion announced that she and husband Alexis Ohanian are expanding their family at Monday night's Met Gala.

Williams, who retired from tennis after last year's US Open already has a daughter, Alexis Olympia Ohanian, Jr., born in 2017.

"[I] was so excited when Anna Wintour invited the 3 of us to the Met Gala," Williams wrote captioning an Instagram carousel of photos of the couple, which included one of her cradling a baby bump.

Social media was soon abuzz as the couple hit the red carpet. For her big reveal, Williams donned a Gucci dress and layers of Tiffany jewelry. 

In an interview on the red carpet with LaLa Anthony for Vogue, Williams said that she was thrilled to finally share her big secret with the world.  

"I'm feeling good now. I can breathe," Williams said. "I can stop hiding."

Williams was candid about her and Ohanian's desire to expand their family in the essay she penned in Vogue magazine last year announcing that she would be "evolving away" from tennis. 

"In the last year, Alexis and I have been trying to have another child," Williams wrote at the time. "And we recently got some information from my doctor that put my mind at ease and made me feel that whenever we're ready, we can add to our family. I definitely don't want to be pregnant again as an athlete. I need to be two feet into tennis or two feet out."

Williams wasn't the only tennis star on the red carpet, nor was she the only celebrity to announce a growing family. Roger Federer, one of the co-chairs this year, was spotted with his wife, Mirka, while model Karlie Kloss also announced her own second pregnancy. 

Williams famously won the 2017 Australian Open, the last of her 23 Grand Slam singles titles, while two months pregnant with Olympia.