Naomi Osaka's older sister has taken to social media to defend the World No.2's position in a post that has since been deleted.
Osaka copped a $15,000 fine on Sunday after skipping her post-match press conference following her first-round victory over Patricia Maria Tig.
She has also been threatened to be defaulted from the French Open if she continues her stance.
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Before the tournament got underway, the World No.2 said she won't be attending any press conferences at Roland Garros because of the detrimental affect they can have on her mental health.
The tennis world has weighed-in on the controversy, which has included World No.1s Ash Barty and Novak Djokovic, as the media attention heightens around the boycott.
Alexander Zverev even appeared to take a dig at the controversy before his First Round match.
And Osaka's sister, Mari, has now weighed-in and defended her sister on a now deleted post.
Taking to Reddit, Mari Osaka tried to explain the reason behind her sister's media boycott.
“Naomi mentioned to me before the tournament that a family member had come up to her and remarked that she’s bad at clay,” she wrote.
“At every press conference she’s told she’s has a bad record on clay. When she lost in Rome r1 she was not ok mentally. Her confidence was completely shattered and I think that everyone’s remarks and opinions have gotten to her head and she herself believed that she was bad on clay.
“This isn’t true and she knows that in order to do well and have a shot at winning Roland Garros she will have to believe that she can. That’s the first step any athlete needs to do, believe in themselves.
“So her solution was to block everything out. No talking to people who is going to put doubt in her mind. She’s protecting her mind hence why it’s called mental health. So many people are picky on this term thinking you need to have depression or have some sort of disorder to be able to use the term mental health."
The post was quickly deleted, but leading tennis reporter Ben Rothenberg confirmed it did come from Mari.
Plenty of fans responded to the post and pointed out Mari's words may have only added to the controversy.
Osaka apologises after post on her sister
Mari then deleted the post, and apologised to her sister and claimed she 'f***ed up'.
"Ok so I f****ed up. My words are coming across so horribly to a lot of people who think taking care of mental health is strategic," she wrote.
"I didn't emphasise the fact that Naomi is dealing with a tone of s**t and honestly fighting for the care of mental health is my post so now a lot of people are taking it as, 'She doesn't want to hear criticism'.
"I'm sorry Namoi I probably made the situation worse."
In a further development on Monday, the four Grand Slams issued a statement to Osaka regarding her media boycott and threatened further action if it were to continue.
"We have advised Naomi Osaka that should she continue to ignore her media obligations, she would be exposing herself to possible further code of conduct infringement consequences," said a statement from the four Grand Slam tournaments on Sunday after she was issued with the $15,000 fine.
"As might be expected, repeat violations attract tougher sanctions including default from the tournament and the trigger of a major offence investigation that could lead to more substantial fines and future Grand Slam suspensions."
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