An Australian boxing doctor has raised concern over allegedly HIV-positive U.S. boxer Tommy Morrison’s return to the sport, months ahead of the former world heavyweight champion’s proposed bout in Melbourne against Australian heavyweight champion John Hopoate, The Sydney Morning Herald reports.

Now 39, Morrison tested HIV positive during a routine blood test in 1996, shortly after signing a $40 million deal to fight Mike Tyson. After testing positive, Morrison was stripped of his boxing license by the Nevada State Boxing Commission.

According to the article, Morrison returned to the ring two years ago, claiming that his diagnosis was the result of a false positive and that his recent tests prove he is HIV negative. The former champ has since had two fights, with recorded technical knockouts in Mexico and West Virginia.

However, Lou Lewis, MD, a consultant for the New South Wales Boxing Authority, told the Morning Herald that he’d demand “at the highest level” that Morrison be forced to undergo an HIV test by an Australian doctor before being allowed to fight.

“He’d be tested for HIV one and two, hepatitis B and C. If he has [HIV] you’d want to protect his opponent,” Lewis said. “Assuming he did have HIV, I would be concerned even sitting ringside. If he had HIV and was cut, you would be worried about his blood going into your eyes. A boxer’s artery can be severed during a fight and his blood spurts everywhere. If Morrison had HIV, it’s a serious concern because the nature of boxing —it is a blood sport—means it has the potential to be very risky.”