Julio Cesar Chavez Jr. (right) lands one of many hard right crosses to the face of John Duddy during his one-sided 12-round drubbing of the durable Irishman on Saturday in San Antonio. Photo / Robert Hughes-Fightwireimages.com.

SAN ANTONIO, Texas — His opponent was made to order, perhaps, but Julio Cesar Chavez left little room for criticism after a dominating 12-round victory over Ireland’s John Duddy on Saturday night at the Alamodome.

That may be the first time anyone’s said that about Chavez (42-0-1, 30 KOs), who was considered an underachiever despite an undefeated record. That’s what happens when you’re the son of a Mexican legend and have an overly protective promoter.

But Saturday, that perception may have begun to change.

Chavez pounded Duddy (29-2, 18 KOs), easily the toughest opponent of his career, early and often. He never was able to knock him down, but he was able to do just about anything he wanted against the Irish banger.

In the process, Chavez showed off some of his newfound skill, courtesy of new trainer Freddie Roach.

The four-time trainer of the year had only a month to work with Chavez, but the results were eye-opening.

“He a very quick learner,” said Roach, undoubtedly best known as for his work with Manny Pacquiao. “He understands boxing. He’s still got a ways to go, but I think he has all the tools to become a world champion.

That may be premature praise, but Saturday offered legitimate evidence.

Duddy is no Pacquiao, but he’s a credible fighter with decent skill.

Chavez won every round, according to one judge, Jurgen Langos, 120-108. Rick Crocker scored it 116-112, while Julie Lederman saw it 117-111.

“This was the best performance of my career,” said Chavez, who was coming off a seven-month suspension after testing positive for a banned diuretic in his fight against Troy Rowland in November. “I think I’ve improved a lot.”

Particularly in the area of conditioning.

Roach said Chavez “got up and ran every morning. He was very disciplined in that.”

Indeed, Chavez seemed to have plenty of stamina left in the final round. He had never gone 12 rounds before, so to be that fresh that late was noteworthy.

Were there areas Chavez still needs to improve? Yes.

“After Julio threw combinations, he stood in front of the guy and let him throw back,” Roach said. “But he didn’t get off first as much as I’d like. He has to do that more.”

Roach said after the first three rounds, he decided to be a little firmer in his instruction.

“I told him he needed to pick it up, to be the aggressor,” Roach said.

Duddy had his best rounds in the fifth and sixth, but Chavez turned it on after that and won going away. There were no knockdowns.

“I knew Julio was going to be a tough fighter,” said Duddy, who got emotional at the podium at the post-fight press conference. “Everyone insisted this was his hardest fight. But he put on a great performance. He put on a great performance and showed he has a very bright future.”

The same might not be said for Duddy, who got hit with everything – left, rights, hooks, jabs. Duddy’s face was lumpy and purple at fight’s end. He attended the press conference wearing shades.

As for Chavez, by winning something called the WBC middleweight silver championship, he becomes the mandatory challenger for champion Sergio Martinez.

Top Rank promoter Bob Arum said Chavez might need another fight before a title shot, a notion seconded by Roach.

“Everything depends on (Floyd) Mayweather-Pacquiao,” Arum said. “If it gets made, it will have a domino effect.”

If it doesn’t, Arum said a Chavez-Miguel Cotto match could be in the cards. If it does, Cotto might take on Antonio Margarito, he said, with Chavez-Martinez a possibility.

Whatever happens at 160 pounds, or possibly 154, Chavez’s name now will at least be in the mix.

In the co-main event, Marco Antonio Barrera returned to the ring after a year’s absence to dominate Adailton DeJesus of Brazil.

Barrera (66-7, 43 KOs), who hadn’t fought since a technical decision loss to Amir Khan in March 2009 when he suffered a 50-inch gash on the top of his head, appeared rusty and out of shape.

But he had more than enough to subdue the light-hitting DeJesus (26-5, 21 KOs), winning by unanimous decision.

There were no knockdowns. Barrera won by scores of 100-90, 98-92 and 99-91.

“I never retired,” Barrera said. “I just took a year off (because of the cut). I’m not in top condition yet, but I was happy with my performance.”