Tokyo Games poster girl Naomi Osaka starts Olympic quest against Zheng Saisai

The four-time Grand Slam winner sees first-round clash pushed back by a day to Sunday by organisers

Naomi Osaka trains in Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka trains in Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka trains ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka hits a backhand during a practice session ahead of the Tokyo Olympics.

Naomi Osaka trains in Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games

Naomi Osaka during a training session at Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka hits a bakhand during a training session at Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka takes a break during training at the Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka hits a forehand during a training session ahead of the Tokyo Olympics.

Naomi Osaka takes part in drills during a training session ahead of the Tokyo Olympic Games.

Naomi Osaka trains on Center Court at the Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka trains in Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka trains in Center Court Ariake Tennis Park ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka hits a serve during a practice session ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka does a rotation drill during practice ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka throws a medicine ball during training ahead of the Tokyo 2020 Olympic Games.

Naomi Osaka runs on the court during training ahead of the Tokyo Olympic Games.

Naomi Osaka plays a point against her coach during training ahead of the Tokyo Olympics.

Naomi Osaka hits a forehand during a practice session ahead of the Tokyo Olympics.

Naomi Osaka during training ahead of the Tokyo Olympics.

After a tough few months on and off the court, Naomi Osaka returns to competitive action on Sunday firmly under the spotlight at the Tokyo Olympics.

The four-time Grand Slam winner and home favourite is back on court after taking a midseason break following her withdrawal from the French Open in May.

Osaka was first fined at Roland Garros for refusing to speak to the media at the tournament, saying the relentless nature of press conferences in tennis was taking a toll on her mental health

The 23-year-old then decided to quit before her second-round match against Ana Bogdan. “I think now the best thing for the tournament, the other players and my well-being is that I withdraw so that everyone can get back to focusing on the tennis going on in Paris,” Osaka said at the time.

“I never wanted to be a distraction and I accept that my timing was not ideal and my message could have been clearer. More importantly I would never trivialise mental health or use the term lightly.”

In a recently released Netflix documentary, Osaka revealed that she is only just starting to come to terms with her celebrity status. “I think the amount of attention I get is kind of ridiculous. No one prepares you for that,” she said. “I always had this pressure to maintain this squeaky-clean image, but now, I don't care what anyone has to say.”

Osaka would subsequently also withdraw from Wimbledon so Games organisers were obviously relieved that the Japanese podium hope decided she was good to go for the delayed and crisis-riven Olympics.

But with all of her major wins coming on hard courts — the same surface being used in Tokyo — Osaka remains widely seen as one of host Japan's strongest gold medal contenders in a field of 64 players each for women's and men's singles that is missing some of the sport's biggest names.

Amid heightened coronavirus pandemic restrictions, Switzerland's Roger Federer and Spain's Rafael Nadal — each with 20 Grand Slams to their names — both pulled out before the Games, along with reigning US Open champion Dominic Thiem.

In the women's singles, two-time Slam winner Simona Halep will be absent, as will American sisters Serena and Venus Williams, who have four gold medals each. Sofia Kenin, Bianca Andreescu and Victoria Azarenka have also decided against taking part, while American teenager Coco Gauff, pulled out after testing positive for Covid-19.

For Osaka, making her Olympic debut, the challenge begins when she takes on China's Zheng Saisai, ranked 52 in the world, in the opening round at downtown Tokyo's Ariake Tennis Park.

The second seed holds a 2-1 career edge over Zheng and their match was due to open the tournament on Saturday but has been pushed by 24 hours to the Sunday, with no official reason yet given for the switch although reports suggest it is because Osaka will be play key role in Friday evening's opening ceremony.

It has been replaced by the match between sixth seed Iga Swiatek and Germany’s Mona Barthel.

"The request came from Tokyo 2020 organisers to move her match to Sunday," an International Tennis Federation spokesperson said on Friday.

Osaka could potentially go on to meet 2020 French Open champion Iga Swiatek in a blockbuster quarter-final, while world No 1 Ashleigh Barty of Australia awaits on the other side of the draw.

In Time Magazine earlier this month, Osaka said she stood by her decision to step away from the court but was now ready to to take on the challenge of competing at the Games.

“I could not be more excited to play in Tokyo,” Osaka, who will defend her US Open title after being confirmed on the entry list for the fourth and final Grand Slam tournament of the season, wrote.

“An Olympic Games itself is special, but to have the opportunity to play in front of the Japanese fans is a dream come true. I hope I can make them proud.”