(USA Today) - Serena Williams announced Thursday she won't defend her Australian Open title.

The 23-time Grand Slam winner said on Snapchat she is “super close” to returning to her championship form five months after she gave birth to her first child.

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Her post read in part:

“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.”

The Australian Open begins Jan. 15. Williams's victory last year was her seventh in Melbourne and her last Grand Slam victory before the birth of her daughter, Alexis Olympia Ohanian Jr.

The Australian Open tweeted best wishes shortly after her announcement, saying in part: "Good luck for the rest of 2018, Serena! We'll miss you."

Andy Murray pulled out of the event earlier Thursday, citing a hip injury. And Novak Djokovic, who has won in Melbourne six times, is undecided on whether he'll play.