Dad-of-10 Yusaf Mack was recorded taking part in the three-in-a-bed romp – but he doesn’t remember the encounter.
Mack, who is engaged to a woman, claims he was drugged before the video was recorded.
The 35-year-old accepted an invite to star in a porn movie because he was short on cash.
He said he arrived at the agreed apartment in New York, US, where there were naked women walking around.
Mack said they gave him a “pill and a shot of vodka”.
The next thing he can remember is waking up on a train which he doesn’t “remember getting on”.
The boxer maintains he had no idea what went on and insisted he’s straight.
He said: “My whole life, I’ve been what they call a whoremonger. I love females.
“The only time I touch a man is when I’m in the ring fighting.”
She said the puncher could have still carried out the sex act because GHP is “a sexual stimulant and some people take it voluntarily to enhance the sexual experience.
“It’s entirely possible to perform and yet not recall.”
Drug expert Trinka Porrata confirmed it is possible for the boxer to have been drugged and not remember the encounter.
Porratta said Mack could have been given the date-rape drug GHB.