LOS ANGELES — Pablo Sarmiento picked the wrong guy to fight after a six-year layoff.

Jessie Vargas, an excellent prospect from Las Vegas who is trained by Roger Mayweather, hurt the 39-year-old veteran from Argentina with a left jab and then stopped him with a vicious barrage of punches only 1:31 into a scheduled eight-round welterweight fight on the Fight Night Club card Thursday at Club Nokia.

Sarmiento (34-14-2, 16 knockouts) has a respectable resume, having once challenged for a fringe world title. And he had a star in his corner, fellow Argentine and middleweight champion Sergio Martinez, with whom he has been working in Oxnard, Calif.

The problem was that he hadn’t been in the ring since 2004, which is a lifetime for a fighter. Stepping through the ropes to face a ferocious young warrior like Vargas was borderline suicide.

Sarmiento looked competent at the opening bell, presenting an awkward style that Vargas had a hard time figuring out initially. And he did hurt Vargas momentarily — albeit accidentally — when his head collided with Vargas’ nose.

However, the first solid punch that found the old man’s face – the left jab – was the beginning of the end.

Vargas (12-0, 7 KOs) pounced on his vulnerable prey in one corner and must’ve landed a dozen hard punches that ultimately put a dazed Sarmiento on his pants, where he stayed. The referee waved off the fight without counting.

“He moved real awkwardly,” Vargas said. “I couldn’t hit him with straight punches. And I didn’t want to get caught coming in. The first time I caught him, though, I knew he felt it. Then I knew I had him.”

Sarmiento might never fight again. Vargas, 21, is just getting started.

The young fighter was asked whether he would’ve preferred to fight a few more rounds.

“What I want is to fight Top-10 fighters, guys like Marcos Maidana and Devon Alexander,” he said. “I know I’m an eight-round fighter. I’m anxious to fight these guys, though. I know I have to be patient. I have to do what my promoter wants me to do.”

In earlier bouts, Jamie Kavanagh, the former Irish amateur star who is trained by Freddie Roach, outclassed Ricardo Malfavon of Santa Ana, Calif., en route to a one-sided four-round decision.

Kavanagh (3-0, 1 KO) landed a number of hard body shots and mixed up his other punches to befuddle his persistent but overmatched opponent. Malfavon (0-3) was never hurt, which raises questions about Kavanagh’s power, but he landed few punches.

The only flaw in Kavanagh’s performance was that he seemed to run out of gas in the closing moments of the fight, which he blamed on sinus problems for which he has taken medication.

Roach wasn’t in Kavanagh’s corner because he’s in the Philippines training Manny Pacquiao.

“I’m happy with my performance,” Kavanagh said. “It’s hard without Freddie here, though. My amateur coach has made the transition to the pros but it’s still hard. He’s in the Philippines training the best fighter in the world pound-for-pound. The timing is just bad.

“You learn something every time, though. So I’m happy.”

Another prospect, Anthony Martinez (6-0, 5 KOs) of Las Vegas, ended his fight with Ronnie Peterson (2-4, 2 KOs) of St. Paul, Minn., with a single left hook to the body 52 seconds into a scheduled four-round welterweight bout.

Peterson, in terrible pain, took a knee and was counted out. Martinez was disappointed in one regard.

“I was hoping he’d get up. I need the work,” he said.

Marcus Robinson of Lancaster, Calif., making his pro debut, defeated Salvador Rios of Santa Ana (1-1) by a split decision in a four-round welterweight fight. Rios is the older brother of prospect Ronny Rios.

And Ramon Valadez (2-1, 1 KO) of Los Angeles stopped Carlos Hernandez of San Fernando, Calif. at 2:15 of the first round of a scheduled four-round lightweight bout.