"It was fairly manipulative and controlling, I really felt like I had no option, that I had to do what he wanted for me to get the best coaching I could."
She also claims Keane sent her sexually explicit text messages including: "Will you show me your panties before you come so I can eye **** you and know what you're wearing?"
According to the girl, who admits to having sex with Keane on three occasions, the tattooed athlete "seemed infatuated" with getting her pregnant.
"I found that really strange. That's when I sort of stepped back a little bit and tried to evaluate what was really going on," she told A Current Affair.
Two other women interviewed have made similar claims. Details of Keane's alleged affairs reportedly emerged on the eve of his wedding to his now wife, Kayleigh.
The Daily Mail reported Keane issued an apology online after the claims emerged.
"I just wanted to take this time to sincerely apologise to you all, I have a serious problem and I have let people down I had a responsibility to you to be a leader and I failed, I am ashamed and embarrassed at myself," Keane posted on Facebook.
Keane is the Australian champion in his division and finished second in the 140 kilogram Pro Division at the World Powerlifting Championships in Moscow late last year.