TOKYO – 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.

The Japanese star’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 2023, giving no reason for her absence.

Osaka’s posts over the past few months have shown her travelling in Europe with her boyfriend, the 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 former world No. 1 spending time practising on court, fuelling speculation that the four-time Grand Slam champion’s tennis career could be over at the age of 25.

Journalist Ben Rothenberg, who has authored a biography of Osaka due out later in 2023, believes she has already taken a “meaningful step back” from tennis and is deliberately keeping quiet.

“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 think she would want to speak that out loud.

“She would sense that it would raise a lot of bells and whistles.”

Osaka has previously talked about struggling with her mental health and revealed she suffered depression. She spent all of 2022 outside the top 10, enduring first-round defeats at the French and US Opens and withdrawing from Wimbledon with an Achilles injury. She is now world No. 47.

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. She 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 47th 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 aged 25.

She explained that she was “spent physically” and no longer had the drive needed to continue.

Osaka has several interests outside of playing tennis, including her sports management agency Evolve, which counts Jabeur and Australian tennis star Nick Kyrgios among its clients.

She has also invested in Pickleball, a tennis-like sport that is growing fast in the United States, and boasts numerous endorsements.

Her website describes herself as not only a tennis player but also “fashion nerd”, “entrepreneur” and “social change advocate”.

Osaka was named the world’s top-earning woman athlete for 2022 by Forbes, with reported earnings of US$51.1 million (S$68 million), even as her tennis career continued to dive.

Another hugely marketable player struggling on court is Emma Raducanu. She said she is trying not to “expect too much” as she bids to return to full fitness in time for the Australian Open after rolling her ankle in a tune-up event last week.

The 2021 US Open champion retired at 6-0, 5-7 in her second-round match against Slovakian Viktoria Kuzmova at the WTA 250 Auckland Classic. She swept the first set in 22 minutes but faltered in the second and had her left ankle examined during a medical time-out before leaving court in tears.

The Australian Open begins on Jan 16.

“I’m just taking a day at a time, honestly, and just trying to, every single day try as best as possible to see and make progress,” the 20-year-old told Tennis Australia in an interview published on Monday.

“And we’ll see hopefully by Monday, or whenever the tournament starts, I’ll be OK and ready. But we’re just taking it a day at a time and not trying to expect too much at this point.”

She added: “It was really unfortunate, to be honest last week, because I was feeling great about my season and I was feeling really good with the preparation I did physically. And I just had an accident on the court, which I don’t know what I could have done to really prevent that.”

After her injury, Raducanu said the indoor courts at the tournament in Auckland were too slippery, with tournament director Nicolas Lamperin responding by saying they were “fit to play”.

However, Danielle Collins, runner-up at the 2022 Australian Open, indicated she might be set for another deep run at Melbourne Park with a 6-2, 6-4 win over Karolina Pliskova at the Adelaide International 2 on Monday.

Earlier, two-time Wimbledon champion Petra Kvitova gave a reminder of her quality when she beat the current holder of the All England Club title Elena Rybakina 6-3, 7-5 to continue her winning start in the new season.

Meanwhile, twice Grand Slam champion and 2020 Australian Open finalist Garbine Muguruza’s struggles continued when she was knocked out early yet again, losing 6-3, 6-4 to Belinda Bencic just days after her first-round exit at the Adelaide International 1.

At the Hobart International, China’s Wang Xinyu posted a 6-4, 7-5 win over Australian wild card Olivia Gadecki. AFP, REUTERS