(CNN) - Serena Williams won't be defending her Australian Open title after the American withdrew from the first grand slam of the 2018 season, saying she needs "more time" after giving birth last year.
The 23-time grand slam winner returned to the court at the Mubadala World Tennis Championship in Abu Dhabi at the weekend, less than four months after becoming a mother, but playing that tournament has given the American pause for thought.
"After competing in Abu Dhabi I realized that although I am super close, I'm not where I personally want to be," the 36-year-old said.
"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."
When Williams won last year's Australian Open she was already two months pregnant.
"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," added Williams. "I appreciate the support and understanding of my fans and everyone at the Australian Open."
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