Serena Williams has given birth to a baby girl, the first child for the former world number one tennis player.
The father of the baby is the 35-year-old American’s fiance, Reddit co-founder Alexis Ohanian.
Serena’s sister Venus Williams confirmed the news before her third round match at the US Open.
“Obviously I’m super excited. Words can’t describe,” she told ESPN.
Venus declined to answer any further questions about the birth following her 6-3 6-4 victory over Greece’s Maria Sakkari.
According to American TV network CBS, Williams was induced on Thursday night.
“Tennis star Serena Williams gives birth to a baby girl weighing 6 pounds, 13 ounces. Mum and baby doing well,” journalist Chris Shepherd wrote on Twitter, citing a source at the hospital.
Williams’ coach Patrick Mouratoglou joined in the well wishes.
“Congratulations @SerenaWilliams for your baby girl. I am so happy for you and I feel your emotion,” Mouratoglou wrote.
“Btw … I wish you a speedy recovery… we have a lot of work ahead of us,” he added.
The birth quickly became the talk of the US Open, which Williams has won six times.
“A baby girl? Well, I hope she doesn’t play tennis,” world number three Garbine Muguruza said with a smile.
Fellow American Sloane Stephens said she expected to see a lot of the newborn.
“I am very happy for her,” she said. “I cannot wait to see the little baby girl on tour because I am sure she will be around.”
It wasn’t just the women players sending their congratulations.
“Congrats Serena!!! So much joy for you!!!” tweeted Rafael Nadal.
Williams, the world’s highest-paid female athlete, was about two months pregnant when she captured her 23rd grand slam singles title at the Australian Open in January, one short of the all-time record held by Margaret Court.
She told Vogue magazine last month about her “outrageous plan” to defend her title in Australia in January.
Other women have left the tour to have children and returned at a high level, although none has done so at Williams’ age.
Court, Kim Clijsters and Evonne Goolagong Cawley all had children before winning grand slam titles when they came back.