Serena Williams withdrew from the Australian Open, the star announced over Snapchat on Thursday.
Defending champion Serena Williams has withdrawn from the Australian Open, saying she is not ready to return to tournament tennis.
Williams was pregnant with her first child when she won last year's tournament at Melbourne Park, the 23rd Grand Slam singles title of her career.
She gave birth to daughter, Alexis, in September.
Williams played in an exhibition tournament last week in Abu Dhabi and indicated after her loss to French Open champion Jelena Ostapenko that she might not make it to Melbourne.
''After competing in Abu Dhabi I realized that although I am super close, I'm not where I personally want to be,'' Williams said in a statement released Friday by Australian Open organizers.
''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.''
Williams, 36, is a seven-time champion of the Australian Open and needs one more Grand Slam title to tie the all-time record held by Margaret Court.
Her withdrawal comes less than 24 hours after fellow former world No.1 Andy Murray withdrew from the men's event with a chronic hip injury.
Several other big names, including top-ranked Rafael Nadal, six-time champion Novak Djokovic and 2014 winner Stan Wawrinka, also are dealing with injuries.
Williams last year beat older sister Venus in the final before revealing she played the tournament despite being more than two months' pregnant.
Australian Open tournament director Craig Tiley said Williams waited as long as she could before letting them know she wouldn't be able to compete.
''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 11th hour to make her final decision,'' Tiley said.
The Australian Open will begin Jan. 15.