NEW YORK — Adam Kownacki now and likely forever will not be winning bodybuilding contests. His specialty is prizefighting, and even if his physique screams “dad bod,” his fists send a surlier message.

Kownacki went to 19-0 (15 knockouts) as he downed ex footballer Gerald Washington in the lead-in to the main event at Barclays Center in Brooklyn, N.Y. on Saturday night.

The Polish born hitter, who grew up in Brooklyn, was 258 on Friday, while the Cali-based Washington (19-3-1, 12 KOs) was 243.

Nine fights had already unfolded, but to the 1,500 or so Poles in the building, this was their main event, all due respect to Keith Thurman. The decibel level was to the point where Jimmy Lennon was all but inaudible to the 9,623 in the joint.

In the first, Kownacki came out banging. High, low, then low again, all behind that sturdy frame which makes him that much more identifiable to the masses. Washington backed up, covered up, and tried some uppercuts. He looked to snake a right around the guard of AK, too. A cut near the left eye of Kownacki didn’t bother him a stitch.

In the second, down went Washington. He got up, and got a long assessment. Kownacki got back to work, flurried, and finished him. The ref hopped in, and he had a stool brought to him. His legs were jello shots.

A left to the body, a seamless hook to the head-right follow went Washington back and a straight right straight up hurt him. A right hand as the loser was up against the ropes dumped him hard to the mat. His eyes were glazed like shots on your 21st birthday glazed. He struggled mightily to rise and the ref made sure he was OK to go, like a cop asking a boozer to walk a straight line. The action re-commenced, but not for long. Two of five shots landed and Washington wasn’t all there.

Kownacki picked up a boatload of new fans making a “gimme a belt” motion and then shouting out love to his on site rooters. There at ringside was WBC heavyweight titleholder Deontay Wilder, who was booed when he was shown on the overhead screen. Wilder fought Washington two years ago and needed five rounds to finish him.

“I trained hard for this fight. I prepared for ten hard rounds, but I’m glad I got it done and ended it as fast as I did,” the winner said to interviewer Heidi Androl.

“I want to thank my team, without them I wouldn’t be where I’m at. I want that belt! We stuck with the game plan. I’m a pressure fighter. I worked on sitting down on my punches and I proved that I have great power when I do that. It’s amazing to have this support from the Polish fans. It definitely gives me extra energy.”