TOKYO, Japan (AFP) — Naomi Osaka has not played a tennis match since September and her withdrawal from next week's Australian Open has raised concerns that the former world No. 1 may never appear on court again.

Osaka's social media accounts have stayed silent since Tennis Australia tweeted on Sunday that the two-time Melbourne champion would miss the first Grand Slam of the year, giving no reason for her absence.

Osaka's posts over the past few months have shown her traveling in Europe with her boyfriend, rapper Cordae, and announcing that her sports management agency had signed up world No. 2 Ons Jabeur.

But there has been little evidence of the Japanese player spending time practicing on court, fueling speculation that the four-time Grand Slam champion's tennis career could be over at the age of 25.

Tennis writer Ben Rothenberg, who has authored a biography of Osaka due out later this year, believes she has already taken a "meaningful step back" from the sport and is deliberately keeping quiet.

"I think she might want to be opaque about it because she doesn't want to put a label on it necessarily," he told AFP.

"I don't think she would use the word 'retiring,' but if she was stepping away from the sport for a while — and it could be for any length of time — I don't know that she would want to speak that out loud."
"I think she would sense that that would raise a lot of bells and whistles."

Osaka has previously talked about struggling with her mental health and revealed that she suffered depression.

She spent all of 2022 outside the top 10, enduring first-round defeats at both the French and US Opens and withdrawing from Wimbledon with an Achilles' injury.

She also split from long-time coach Wim Fissette last summer, replacing him with her father Leonard Francois.

Her last appearance was at the Pan Pacific Open in Tokyo in September, where the home favorite withdrew before her second-round match, complaining of abdominal pain.

She told reporters at that tournament that she had gone through "more down than up" in 2022 and that she had "learned a lot" about herself.

She is now ranked 47 in the world, having hit the summit for the first time in 2019.

Rothenberg believes Osaka is "recalculating things" and may decide that she is not prepared to make the sacrifices needed to continue as a professional tennis player.

"For her, the math is not adding up right now, for her to want to make the commitment," he said.

"She knows how much work it is and how all-encompassing and preoccupying it is to be an active full-time player with the standards that she has."

"She's won so much already, she's not going to be content just to be a top-20 player again."

Australia's Ashleigh Barty, then the world's undisputed No. 1, stunned the tennis world in March last year when she announced her retirement at age 25.