Father Legend has some lessons for Julio Cesar Chavez Jr.

LAS VEGAS – There was a time when the son couldn’t mention his father’s name. It was too painful. Legends don’t die. But dads do.

It was 2010. Julio Cesar Chavez Jr. watched substance-abuse wash away the immortality that Mexicans have attached to his famous dad, Julio Cesar Chavez Jr.

“I kept thinking this guy is going to die,’’ Chavez Jr. said Wednesday to handful of reporters after a formal news conference for his middleweight title fight Saturday night against Sergio Martinez at Thomas & Mack Center. “He’s going to die. I got used to thinking about it.’’

Dad changed his son’s mind, but only after the end so feared by his son ominously appeared one day in Tijuana. Julio Sr. said he didn’t feel well. His son recalls that he sought medical help. His father was sedated and then rushed to rehab.

Twenty-six months later, Julio Cesar Chavez Sr. sat Wednesday – clean, sober and proud — near his son just days before the family business continues against Martinez in an HBO pay-per-view bout.

“Right now, our relationship is good,’’ said Chavez Jr., about a 2-to-1 underdog in betting odds posted late Wednesday. “It can withstand the disagreements we have.’’

The relationship has healed so much that the son can now often joke about a dad who doesn’t often like to be the intended target of any sort of mockery. Julio Chavez Sr. has been in gym with his son and trainer Freddie Roach. But Chavez says he listens only to Roach. The son is a smart guy. He knows that old lesson about dads, even Hall of Fame Fathers. They don’t belong in their son’s corners.

“Freddie is the last word,’’ Chavez Jr. said. “Sometimes, my dad will run to my corner and say something. I’ll tell him: ‘Work the corner or get the hell out.’ ‘’

Dad always gets the message, Julio Jr. said.

At least, he does now.

A couple of years ago, he wasn’t certain. His father, he says, would come home early in the morning after a night of drinking.

“He would come home, sometimes at 5 a.m. and sometimes on the day I’d fight, sit down and start talking, while I was trying to sleep’’ he said. “He’d just talk and talk, talk for three and four hours.’’

About what?

“Not sure,’’ Chavez said. “About everything.’’

In the couple of years since his dad underwent rehab, Julio Jr., once dismissed as a lazy rich kid, began to mature as a fighter under Roach’s steady guidance. His training schedule might be quirky. Roach said he often trains in the early morning hours. Workouts can start at 1 a.m. and end 4 a.m. But the work is serious, Roach said.

In part, Julio Jr. appears to have inherited some his dad’s toughness. There’s the durable chin. There are also the body punches. Both made a Hall of Famer out of his stubborn dad.

“That’s why I feel sorry for Sergio Martinez,’’ Bob Arum, Julio Jr.’s promoter, said Wednesday during the news conference. “He’s going to take body shots like he’s never felt before.’’

But there can also be dangers in what a son inherits from his dad. For Julio Jr., it is a lifestyle that put his dad in rehab. A warning sign was there in January when The Ring’s Lem Satterfield reported that Julio Jr. was charged with DUI within a couple of weeks of his victory over Marco Antonio Rubio.

It was a lesson then.

It’s a lesson now, especially for a family business that needs to remember them if it hopes to fight on.