"I can compete - but I don't want to just compete". The tennis star, who was eight weeks pregnant with daughter Olympia when she won her seventh Australian Open title a year ago, confirmed that she would not be returning to the court as she "needs more time".
He was due to take part in an exhibition match in Abu Dhabi and was also scheduled to defend his Qatar Open, but had to withdraw due to elbow pain.
Novak Djokovic is slated to play two exhibition events before taking a final call on his participating at the Australian Open which begins from January 15. She won in 2003, 2005, 2007, 2009, 2010, 2015 and 2017.
After Andy Murray and Kei Nishikori, Serena is the third big name to pull out of the season opening Grand Slam, starting later this month.
Williams is the latest big-name player to withdraw from the year's opening grand slam, which will be played from January 15-28, with Britain's Andy Murray (hip) and Japan's Kei Nishikori (wrist) having already said they would not compete.
Serena will sit one out, but is promising to return in future.
Williams said she isn't ready for top level tennis just yet.
There is also uncertainty over whether former champions Novak Djokovic and Rafael Nadal, the latter of which arrived in Melbourne earlier on Friday, will be fit to take to the court.
"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", he said.