Saturday 2 September 2017 21:49, UK
Former world No 1 Serena Williams has given birth to a baby girl, her coach Patrick Mouratoglou said on Twitter.
"Congratulations @SerenaWilliams for your baby girl. I am so happy for you and I feel your emotion, " Mouratoglou wrote.
"Btw @serenawilliams I wish you a speedy recovery… we have a lot of work ahead of us," he added.
Her sister Venus told ESPN: "Obviously I'm super excited. Words can't describe."
Fellow players have been having their say at the US Open. World No 3 Garbine Muguruza said: "A baby girl? Well, I hope she doesn't play tennis."
Fellow America Sloane Stephens said: "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."
Williams, 35, who is engaged to Reddit co-founder Alexis Ohanian, last competed at the Australian Open in January when she was about two months pregnant. She won a record 23rd Grand Slam singles title without dropping a set in Melbourne.
She told Vogue magazine last month about her "outrageous plan" to defend her title in January.
Other women have left the tour to have children and returned at a high level, although none have done so at Williams' age.
Kim Clijsters of Belgium retired and had a child before coming back at the age of 26 and winning three Grand Slam titles while Australians Evonne Goolagong Cawley and Margaret Court also won Grand Slam titles after having children.
Sky Sports Tennis will have all the action from the US Open covered via our website sky.mnosports.com/tennis with our live blogs and updates throughout the fortnight as the Grand Slam year reaches its climax.
On the move? Head to our app for mobile devices and iPad, or follow our Twitter account @SkySportsTennis to join in the conversation. Who will win the US Open titles this year? Have your say...
We will also have coverage of the World Tour Finals in November with every match live on Sky Sports.
