Two-time champion Naomi Osaka has pulled out of the Australian Open, the organizers of the season's first Grand Slam which will begin on January 16 announced on Sunday, without giving a reason for the Japanese star's withdrawal.

"Naomi Osaka has withdrawn from the Australian Open. We will miss her at AO2023," the Australian Open said on Twitter. "Dayana Yastremska moves into the main draw."

The Melbourne champion for 2019 and 2021, Osaka has not played a competitive match since pulling out of her match against Beatriz Haddad Maia due to abdominal pain in the second round of Pan Pacific Open in Tokyo in September. 

She has since slumped to 42 in the world rankings.

Veteran American Venus Williams will also be a no-show after injuring her ankle and knee at last week's Auckland Classic. 

Meanwhile, for Daniil Medvedev, the winning chances at the upcoming event are high after U.S. Open champion and world No. 1 Carlos Alcaraz also withdrew on January 6 with a right leg problem.

Medvedev believes he has the weapons to beat the "best in the world" Novak Djokovic despite being outplayed by the Serbian star in Adelaide in their latest clash.

The Russian, a losing finalist at the last two Australian Opens, crashed 6-3, 6-4 to a dominant Djokovic on Saturday in the Adelaide International semi-finals, a warm-up event for the Australian Open. 

"Every time I play them (Djokovic and Rafael Nadal), before the match the only thought is I have to win, I have to try my best to win," Medvedev said after an under-performing 2022, where he dropped to seventh in the world rankings.

"I managed to do it. Rafa I think I beat only once, but still I managed to do it. I had some tough matches against him. Against Novak I won a Slam," he added.

Since defeating Djokovic for the 2021 U.S. Open title, Medvedev has been beaten three times by the Serb, who is back in Australia after missing last year's Australian Open because of his vaccination status.

Djokovic, 35, will meet a first-time opponent in the final at Adelaide International: 22-year-old American Sebastian Korda, who led Yoshihito Nishioka 7-6(5), 1-0 when the Japanese retired due to a right hip injury.

(With input from agencies)