Serena Williams welcomes first child with fiancé Alexis Ohanian

Tennis star Serena Williams has given birth to her first child with fiancé Alexis Ohanian, her sister Venus has confirmed.

After reports that Serena had given birth, her sister finally confirmed the lovely news before her match at the US Open, saying: 'Obviously I'm super excited. Words can't describe.'

Serena was reportedly admitted to St Mary's Medical Center in West Palm Beach, Florida, on Wednesday, where she welcomed a healthy baby girl.

The new parents are yet to confirm the news themselves, and reveal the baby name they picked for the baby girl, but their friends and family have been filling social media with well-wishes.

Many personalities from the world of tennis took to Twitter to congratulate them on their new arrival, including Rafael Nadal, who wrote: 'Congrats Serena!!! So much joy for you!!!'

Patrick Mouratoglou, Serena's tennis coach also congratulated the new mum after the news broke, writing: 'Congratulations @SerenaWilliams for your baby girl. I am so happy for you and I feel your emotion. Recover well & enjoy without limitation. Btw ... I wish you a speedy recovery... we have a lot of work ahead of us.'

Beyoncé, who recently welcomed twins herself, was also one of the celebrities who took to Instagram to congratulate Serena on her new baby.

Posting a picture of the new mum in a beautiful white gown, still showing off her baby bump, the Crazy in Love singer wrote: 'Congratulations Serena!'

Serena announced she was expecting her first child back in April, with a picture of her bump on Snapchat. She then explained she made the announcement by accident, but confirmed that she was indeed expecting a baby with her fiancé Alexis Ohanian, who's the co-founder of Reddit.

And even though the mum has just welcomed her first baby, she revealed in a recent interview that she plans to get back to training in November and compete in the Australian Open in January.

'I am looking forward to becoming a mother and coming back to the courts already. I'm always thinking about what's next: the next victory, the next trophy', she told The Telegraph.

The transition back into the courts will be probably be easy for the new mum, as she's kept active throughout her pregnancy and often posted pictures of herself playing tennis on social media.

Fans of the tennis pro have already started speculating on Serena's daughter tennis abilities, with many saying it's likely she'll take after her mum - but we'll have to wait and see!