Serena Williams has announced that she will not be defending her title at the Australian Open.

Serena beat sister Venus in the 2017 final in Melbourne, and later revealed that she was pregnant.

The 36-year-old gave birth to daughter Alexis Olympia in September, and returned to the court in an exhibition match against Jelena Ostapenko in Abu Dhabi at the end of December.

In a statement on Snapchat, she wrote: “After performing in my first match after giving birth I realised that although I am super close I’m not where I personally want to be.”

She added: “My coach and team always said ‘only go to tournaments when you are prepared to go all the way’. I can compete – but I don’t want to just compete, I want to do far better than that and to do so, I will need a little more time.

“With that being said, and even though I am disappointed about it, I’ve decided not to compete in the Australian Open this year.

“The memory of last year’s Open is one that I will carry with me, and Olympia and I look forward to coming back again. I appreciate the support and understanding of my fans and everyone at the Australian Open.”

Australian Open tournament director Craig Tiley said in a statement: “The true champion Serena is has been demonstrated in the herculean efforts she has made over the past few months in her desire to play the Australian Open.

“Serena transcends the sport in the way she approaches all aspects of her life and consistently gives her all in everything she does. It was never going to be good enough for her to just compete, she wants to give herself the best chance to win.

“I’ve been in constant contact with Serena and her team and know this is why she has pushed it and pushed it until the eleventh hour to make her final decision.

“We all wish her the very best and I look forward to seeing her back on court this year, and can’t wait to welcome her back to the Australian Open in 2019.”

This week, Williams refused a wildcard for next week’s Sydney International – and confirmed later that she would not be competing at the 2018 Australian Open.

Serena’s withdrawal is the latest setback for what had been a hotly anticipated Australian Open. British number one Jo Konta is an injury doubt, while on the men’s side Andy Murray has pulled out with a hip injury and Kei Nishikori is suffering from a wrist problem, and there are question marks over the fitness of Novak Djokovic (elbow) and Rafa Nadal (knee).