Serena Williams reportedly gave birth to a baby girl Friday at a hospital in Florida.
Williams, who announced her pregnancy in April, won the Australian Open in January while several weeks pregnant. Her older sister, Venus, who won her third-round U.S. Open match on Friday, told ESPN before play started that she was "super excited" about her sister giving birth.
As news of Serena's delivery spread, the tennis community (and Beyonce!) took to social media to congratulate the 23-time Grand Slam champion.
Williams is expected to return to tennis next year.