Two-time Australian Open champion Naomi Osaka on Sunday pulled out of the opening Grand Slam of the year just over a week before it starts, organizers said.

"Naomi Osaka has withdrawn from the Australian Open. We will miss her at AO2023," the tournament said on Twitter. No reason for the Japanese star's withdrawal was given.

It was another big blow for the tournament after US Open champion and world No 1 Carlos Alcaraz also withdrew on Friday with a right leg problem.

Veteran American Venus Williams will also be a no-show after picking an injury at last week's Auckland Classic.

The champion in Melbourne in 2019 and 2021, Osaka has not played a competitive match since pulling out of a tournament in Tokyo in September with abdominal pain and has slumped to No 42 in the world rankings.

The four-time Grand Slam winner has previously talked about struggles with her mental health and spent all of 2022 outside the top 10, enduring first-round defeats at both the French and US Opens.