Story highlights Fallon Fox became a woman through surgery in 2006

She won her first two fights in the first round

She revealed her operation to SI after another publication looked into her surgery

Her last opponent is appealing the loss, saying Fox failed to disclose background

Born a man, Fallon Fox became a woman through surgery and then trained to fight in mixed martial arts.

Now that she has won her first two MMA bouts -- both in the first round -- she has gone public as a transgender fighter, the first on record in a popular sport that some consider as the successor to boxing.

"The reaction has been positive," said Fox, 37, who revealed her story recently to Sports Illustrated after a journalist with another publication began to investigate her private surgery. "It's just some people, some of society doesn't get it yet. And this is what we're trying to do now is to inform people and let them know about transgender athletes."

When asked if it's fair for a man-turned-woman fighter to face another woman in the ring, Fox said Saturday there were "no unfair competitive advantages."

What was unfair, her last opponent and her manager say, is how Fox didn't disclose until after the fight that Fox had a sex change operation.

That opponent, Ericka Newsome, was knocked out this month with "a tie clinch," or a knee to the chin, 39 seconds into the fight without anyone knowing of Fox's background.

It was "unfair I didn't know it, but it didn't matter that she fought me," Newsome told CNN. "I feel that it should have been disclosed to me ahead of time...so we are aware and able to be better prepared for the situation."

She and her manager are going to appeal the loss in Florida on the grounds of how Fox failed to disclose being a transgender person and how the referee stopped the fight too early.

"They should have let the fight go," manager Matt Hamilton said. "She should have thrown at least one to two more shots to confirm it. On that particular basis, that's one of the things we'll appeal with, as well as not having it disclosed."

Meanwhile, the California State Athletic Commission is reviewing a claim by Fox that the state gave her a fighting license in 2013 when in fact the commission says her license application is still being reviewed, Sports Illustrated reported.

Fox subsequently told Florida authorities that she had a California license, and now the Florida boxing commission is also reviewing Fox's license application, the magazine reported. Also, Fox admitted she didn't disclose to boxing authorities she is a transgender person but added she wasn't asked to either, the magazine said.

Sports Illustrated writer Loretta Hunt wrote of Fox's 2006 gender reassignment surgery and winning her pro debut in May 2012. Hunt told CNN that guidelines for the Association of Boxing Commissions are similar to the International Olympic Committee's policy that allows transsexuals to compete in Olympic games. The IOC requires transgender athletes to undergo hormone therapy long enough to remove gender-related advantages.

In fact, Hunt said, mixed martial arts guidelines don't require a sex-change surgery, but they do require two years of hormone therapy for transgender fighters.

"Whether it comes after the surgery or it's just on its own, that must be done and you must be tested throughout the two years," Hunt said. "Those papers must be submitted to the athletic commission for review."

Newsome wants to fight Fox again, Hamilton said.

"We would love a rematch," Hamilton said.