Viewers tuning in early to the Mike Tyson vs. Jake Paul boxing match were just treated to quite the sight -- Iron Mike's bare ass!!

The scene unfolded merely minutes ago inside an AT&T Stadium locker room ... as the 58-year-old legend was giving a pre-fight interview to his son, Amir.

The younger Tyson tried to ask his Pops for his thoughts on the impending tilt with El Gallo ... but Mike wasn't offering up much. So Amir requested a prediction, and when Mike said he'd score a "vicious win" -- the two concluded the interview with "I love yous" and a kiss.

For some reason, though, the cameras stayed on Mike as he walked away from Amir -- and because he was wearing nothing but a jock strap ... everyone following along on the Netflix stream got a great look at Mike's cheeks.

The images all went down during Katie Taylor's scrap with Amanda Serrano ... and the fight's broadcasters didn't mention it -- but check out X, plenty of people sitting at home certainly noticed.

Mike's fight with Paul is now just minutes away -- here's to hoping he finds some shorts between the locker room and the ring!