Australian tennis hero Jelena Dokic has sent a warning about her new documentary Unbreakable: The Jelena Dokic Story.

The film will be premiered in Brisbane on Sunday (tomorrow) ahead of its November 7 release, and Dokic says people will find it “hard to watch”.

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Obviously, Dokic is not trying to put people off, but the content is — without a doubt — chilling and raw.

Dokic called it “heartbreaking” and “horrific” and “disturbing”.

But she insists “hard stories” have to be told if you want to make change.

In the documentary, Dokic recalls a time when she was brutally beaten up by her father, Damir, after losing a match.

“I remember he was so mad that he goes into the bathroom with me, locks the door, and he beat the crap out of me,” she said.

“He slammed my head against the wall multiple times. He was kicking me. My shins were so bruised, I couldn’t walk. He actually punches me in the head. And then I went unconscious for a little bit. He also stepped on my head as well.”

But speaking to News Corp, Dokic also made an extraordinary admission about Damir, the man who subjected to show much torment.

“I don’t blame anyone. I don’t resent anyone. I definitely don’t hate anyone, never would,” she told News Corp.

“I’m not bitter about it. Even to my father, which people find surprising. But I don’t hate him. I don’t necessarily forgive him, but I don’t hate him.”

Unbreakable is also the title of Dokic’s first book.

It documents her life from a young kid under the control of her abusive father, all the way through her tennis career and eventual attainment of peace and happiness.

The producers of the documentary say it is a story of Jelena’s “extraordinary survival”.

“The trailer for Jelena Dokic’s Unbreakable documentary is so chilling,” tennis account Christian’s Court said its release.

Dokic is very open and vocal about her mental health struggles and the abuse she received from her autocratic father growing up.

She has also been lauded for her work in the body image space, advocating for all people to feel comfortable in their own skin.

Dokic, a former world No.4 and Wimbledon semi-finalist, has never been afraid to call out her critics.

She has faced a constant battle with body shaming, especially online, but has made it her mission to support body image acceptance in others.

But Dokic says she has never been happier and is grateful the way her story has been received.

She says by sharing her story she has reclaimed her life and for the first time has found freedom.

She believes there are many dark secrets in tennis and other sports and she hopes her story will inspire victims to speak up.