Naomi Osaka of Japan poses with the Chris Evert WTA World No.1 trophy during day three of the Miami Open tennis in Miami Gardens, Florida, on Wednesday. Julian Finney/AFP
MIAMI: World number one Naomi Osaka refused on Wednesday to become embroiled in a dispute with one of her former coaches who is suing her for 20 per cent of her career earnings.
Christophe Jean, who helped the Japanese two-time Grand Slam champion when she was a junior, wants at least $2 million of the $10 million of her earnings to date.
Jean insists Osaka's father, Leonard Francois, had signed a contract when he was coaching the 21-year-old and her sister Mari in 2011.
Osaka told AFP she was "not allowed to say anything" about reports of the lawsuit, although sources close to the Japanese star stressed they are not fearful of the outcome and believe the matter will be resolved shortly.
When asked about the difficulty of dealing with the trappings of fame and becoming the world's top player, however, Osaka admitted she is still learning.
"I am still relatively new at this so I can't really say yet," she said.
"But maybe as more time goes on I will be able to get a better grasp of the situation," she added.
Japan's Naomi Osaka poses with her trophy after winning her match against Czech Republic's Petra Kvitova at Melbourne Park, Melbourne, Australia. File / Reuters
TMZ, which reported the lawsuit, says Osaka attorney Alex Spiro calls Jean's claim "absurd" and adds: "This case has no merit and we will move past it."
Osaka spoke as tournament play began at the Miami Open, being staged at Hard Rock Stadium, home of the NFL's Miami Dolphins, for the first time after decades at Key Biscayne.
After losing in the round of 16 while defending her title at Indian Wells, Osaka hopes to regain the form that has seen her win the past two Grand Slam titles at this year's Australian Open and last year's US Open.
"Everyone knows that Indian Wells and Miami are like two slams so I feel there is a lot of motivation to win these tournaments," Osaka said.
"Beating Serena Williams in Miami last year was such a good memory -- the first time I had played her -- and I came straight off winning Indian Wells. I just wanted to test myself against her and from then on it felt like a dream.
"To win here would mean so much. I grew up watching so many great players winning here and was actually in the stands for one of the finals. Just to come from being a kid in the audience to be the person holding the trophy would be special."
There have been 13 different winners in 13 WTA events so far this year, with Canadian teen Bianca Andreescu the first wildcard to win at Indian Wells.
Osaka, whose sister Mari was due to face American Whitney Osuigwe in the first round, is on her guard.
Naomi Osaka of Japan fields questions from the media at a player availability session on Day 3 of the Miami Open Presented by Itau on Wednesday in Miami Gardens, Florida. Michael Reaves/AFP
"Everyone is really motivated by whoever wins the week previous and you can see that," she said.
"Everyone is at the same level so it comes down to who wants it the most and is willing to put in the work," she added.
New home for event
The $72 million spent on turning a former Super Bowl stadium into a tennis venue has received good reviews from players.
A 13,800-seat main court -- where former world number one Victoria Azarenka defeated Dominika Cibulkova 6-2, 3-6, 6-4 -- has been created while 10 other courts have been built atop parking lots.
"I've never imagined ever playing tennis at Dolphin Stadium," Osaka said. "We actually drove past it a lot when I was a kid. There's a lot space here, which is good."
Defending champion Sloane Stephens celebrated her 26th birthday on Wednesday and admitted she struggled to find the new venue.
"I didn't even know where this place was," Stephens said. "When I drove here this morning, I drove to the Hard Rock Hotel.
"I've been going (to Key Biscayne) since I was 14 years old. Sad times. We're going to miss it. But they worked so hard on this venue and it looks great so far."
Simona Halep kept alive hopes of regaining the world number one ranking Sunday, beating Polona Hercog 5-7, 7-6 (7/1), 6-2 to reach the last 16 of the WTA and ATP Miami Open.
The 37-year-old Swiss can clinch a record-extending 21st major if he manages to break free of the world number one's stranglehold.
Tennis star Serena Williams has revealed that she has apologised to Japan's Naomi Osaka who defeated her in the finals of the US Open last year.
England were struggling in pursuit of a victory target of 277 after collapsing to 117-5 on the fourth day. But man-of-the-match Woakes, who had helped drag England back into this contest with 2-11 in just five overs late on Friday, and fellow World Cup winner Jos Buttler turned the tide with a stand of 139.
Chelsea winger Christian Pulisic faces six weeks out with a right hamstring injury that could see him miss the start of the English Premier League.
Maurizio Sarri’s reign as Juventus coach ended Saturday after just one season, the veteran manager paying for the Italian team’s premature Champions League exit.