LAS VEGAS — Fernando Vargas Jr. helped build Allegiant Stadium with his own two hands as a construction worker before his burgeoning boxing career kicked off five years ago, and on Saturday he was featured in the co-main event of the superfight featuring Canelo Alvarez and Terence Crawford.

Standing in the opposite corner was the Freddie Roach-coached Callum Walsh. The 24-year-old Irishman came into clash looking to prove he's the real deal and a top talent, and that he wasn’t in a favorable position due to his longtime affiliation with UFC and TKO president Dana White.

After 10 competitive rounds between southpaw junior middleweight contenders, Walsh (15-0, 11 KOs) did more than enough in the eyes of the judges to beat Vargas (17-1, 15 KOs) by unanimous decision via scores of 100-90, 99-91 and 99-91.

With the win, Walsh solidified his long-saved seat as a future face for Zuffa Boxing, which plans to feature nearly a dozen shows a year featuring some of the sport’s up-and-coming contenders.

Walsh and Vargas had solid moments in the fight but it was never intense, nor did they gain any considerable momentum or separation. They came into the contest without having beaten elite competition, and they clearly were each others’ best opponents to date in an evenly matched fight that went punch for punch.

In a feeling-out first round, Vargas dropped him with what appeared to be a right hook to the chest, but referee Harvey Dock ruled it a slip and Walsh immediately bounced back on his feet.

Walsh worked the body well in the second and third rounds and by the fourth was splitting the guard of Vargas with his left hand. While Walsh was busier, Vargas was more calculated and answered with one-twos.

Through the first five rounds, Walsh threw 339 punches and landed 74, compared with 64 of 180 for Vargas, per CompuBox.

Vargas, 28, the son of two-time junior middleweight titleholder Fernando “El Feroz” Vargas, fed off the thousands of Mexican fans in the arena, who oohed and aahed anytime he landed anything significant. Still, those moments were few and far between.

Looking to close the show strong, Walsh dialed up the pressure in the eighth and ninth rounds by throwing more than 100 punches in each frame.

Vargas, meanwhile, started to slow, as he was fighting past the seventh round for the first time in his career. He didn’t appear to be fighting with the same vigor as he did in Rounds 4-7, which featured his best moments in the fight.

In the 10th, Vargas lunged in and Walsh made him pay with a whipping left hook to punctuate his win, ultimately outlanding him 182-159.