Serena Williams out of Australian Open

Seven-times champion Serena Williams has withdrawn from the Australian Open, four months after giving birth to her first child.

Serena Williams has demanded an apology from Tennys Sandgren. Source: AAP

Seven-times champion Serena Williams has withdrawn from the Australian Open.

The 23-times major winner and women's titleholder gave birth to her first child last September and says she's not yet ready to compete.

Williams made her decision after losing an exhibition match last week in Avu Dhabi to French Open champion Jelena Ostapenko.

"After competing in Abu Dhabi, I realised that although I am super close, I'm not where I personally want to be," Williams said on Friday.

"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."

Williams joins high-profile male players Andy Murray and Kei Nishikori to bypassing the Australian Open due to injury.