The two pugilists squared off in a ring inside AT&T Stadium in Arlington, Texas on Friday night ... and, initially, Iron Mike looked good.

The 58-year-old came out swinging in the first round ... and appeared to win it on the judges' scorecards.

But, as the two-minute rounds wore on ... Tyson's age showed. He bit down on his gloves repeatedly and stopped moving with pace. At times, he simply stood flat-footed, as Paul threw flurries of punches his way.

The 27-year-old Paul seemed to win all six of the final rounds -- and in the last few seconds of the eighth, he actually paused the action to bow and show his respects to Mike.

Jake showed up to the tilt in a diamond-studded silver fit in a custom car with his brother, Logan. Mike, meanwhile, headed out to the ring with little fanfare in an all-black getup.

The crowd featured a ton of A-list celebs, including Jerry Jones, Shaq, Michael Irvin, Rob Gronkowski, Josh Duhamel, Charlize Theron, Joe Jonas and Micah Parsons.

After the match, Mike hinted this wouldn't be the last time we see him in the ring ... he actually called out Logan!