Mario Barrios stretches toward a 140-Pound world title

Marrio Barrios transformed from a skinny kid, easily overlooked, to the most formidable prospect in the 140lb division. (Lucas Noonan / PremierBoxing Champions)

Mario Barrios was skin and bones as a senior in high school. He stood around 5-foot- 7, and with his spaghetti-thin arms and legs may have weighed about 117 pounds. Barrios didn’t even tell people he boxed—and those that knew still found it hard to believe.

Even today, people who knew him back then can’t comprehend what the scrawny kid has transformed into: one of the best, young 140-pounders in the world.

He continues to be on the stringy side, at 5-11, though he’s able to fit the weight inside a lithe frame. It’s as if Barrios is all arms and legs. Add his unusual reach and height advantage over almost everyone he faces with a slayer instinct he adopted through time from his older sister, Selina, and mother, Isabel Soto, and Barrios is an incredibly formidable opponent.

The world will get another glimpse of the fast-climbing 22-year- old when he takes on Naim Nelson (13-3, 1 KO) at the Sands Bethlehem Events Center, in Bethlehem, Pennsylvania, as the main event in a scheduled 10-round junior welterweight clash on the Premier Boxing Champions show on “Toe-to- Tuesdays’’ on FS1, on September 19.

Barrios (19-0, 11 KOs) will be making his fourth foray as a junior welterweight and he couldn’t feel any stronger than he does now. It’s no coincidence that he’s stopped his last three opponents. And despite the fact Nelson has lost three of his last four, he’s never been knocked out (Tre’Sean Wiggins defeated him by a fifth-round technical decision back in April).

“He has one knockout, but we aren’t taking anything away from him,” Barrios said of Nelson. “I believe anyone who steps in the ring is dangerous. It only takes one punch to change a fight. I’m confident that I go in and take care of business. He’ll try to box and use speed. He may try to catch me with one shot here and there. It all depends on what fighter shows up that night. I’ll tell you this, no matter what fighter does show up on September 19, we’re going to be well prepared for it. Throughout this past year, I really learned how to use my jab.’’

Barrios has been working with noted trainer Virgil Hunter for the last four fights. For Barrios it’s like a graduate level course in boxing.

“Working with Virgil Hunter, he’s taught me a lot. He’s educated me on jabs, not using it to hit the other guy but to use it as a distance finder. I also feel way stronger at 140,’’ Barrios said. “When I first started at 130, I was making the weight naturally, but fight after fight, as I got older and bigger, it was becoming harder.

“My last fight [at 130 against Devis Boschiero] was very difficult and in the later rounds I didn’t have the power in my legs. That convinced me that I couldn’t fight at 130 anymore. I still could have made 130, but it wouldn’t have been good for my health and overall career. I feel good at 140; super strong and ready to do something in this weight class. I’m growing more and more as a fighter and ready to show everyone some things I haven’t shown before.”

“ I feel good at 140; super strong and ready to do something in this weight class. I’m growing more and more as a fighter and ready to show everyone some things I haven’t shown before. ” Mario Barrios

Barrios arrived here through an odd introduction from someone unexpected. His mother Isabel grew up a fight fan watching the legends on TV with her father. Isabel aspired to box, but in the 1980s and ’90s there were barriers women were faced with. She never got the chance, though she made sure her children, Selina and Mario, would.

When Mario was six and Selina eight, Isabel took them to the Eastside Boys and Girls Club in San Antonio, Texas. The two stood there, eyes bugged out, absorbed by the synchronized rhythm of speed bags being hit and cacophony of clanging chains as fighters whomped on the heavy bags.

“I was a kid, I had no idea what I was getting into,” Mario said, laughing. “I can’t say I was interested in [boxing] at the time, but it was something that I was open to learn. I remember when we first walked in the gym and these grown men were hitting speed balls, and doing mitts. I was in shock. I was 55, 60 pounds and they thought my sister would be 6-foot. There was no way that I would step into the ring with her when I was little. She’d beat my ass.

“She’s the one who naturally had that killer instinct. My sister and I would go to tournaments and she would literally win every one. Me, I just wanted to box. I never won anything.”

What changed everything for Barrios—moving into the national spotlight, becoming the best in his own family—was winning the 95- pound PAL national title when he was a freshman in high school. Until then, Barrios was the kid who always finished second or third, not quite good enough to breach the threshold and win.

“It’s then that I started to realize I was pretty good at this,” Barrios recalled. “By the time I was a senior, I was 5-7, fighting at 123, even though I was always lighter than that, more like 116, 117. It’s funny, because no one believed I was a boxer because of my build. But each year I grew an inch. I might still be growing. A lot of people I went to grade school and high school with freak out when they see how tall I’ve become and where my career is.”

There is a good chance they’ll believe that he’s a fighter now.