By Keith Idec

NEW YORK — Bob Arum made sure to present Julio Cesar Chavez with a cake commemorating his 50th birthday when the press tour for his son’s career-defining fight stopped in Manhattan last week.

Arum also gave Mexico’s most famous fighter a lot of credit for helping Julio Cesar Chavez Jr. become the type of middleweight the Hall-of-Fame promoter could match against Sergio Martinez without worrying that he’d be embarrassed. That couldn’t have happened a couple years ago, when the younger Chavez couldn’t be trusted to train properly and the elder Chavez couldn’t be counted upon to help his son change the bad habits that prohibited him from reaching his potential.

“The thing that’s most important is that [Chavez Jr.] believes he can win the fight and his father believes he can win the fight,” Arum said of the Chavez-Martinez HBO Pay-Per-View showdown Sept. 15 in Las Vegas. “And the father has been, over the last year or so, an extremely positive influence. The father has taken a real role in his training, in his preparation. For the last fight [against Andy Lee], the father spent all the time in El Paso, all the time at the training camp in Vegas.

“The father has been a very positive thing, and a few years ago that wouldn’t have been possible because the father had terrible substance-abuse problems himself. And now, and he has been for the last couple of years, he is clean. Clean, sober. I was telling [a Top Rank publicist], ‘Imagine if this was a few years ago?’ The guy was uncontrollable. And now, it’s a pleasure to be around him. You talk to him, he obviously he knows the sport, and it’s a pleasure having a conversation with him.”

The elder Chavez finished his illustrious, Hall-of-Fame career 107-6-2, including 86 knockouts. He won the first 87 fights of a career that spanned nearly 22 years, captured six world titles in three divisions and is generally regarded as one of the top boxers in the history of the sport.

His father’s resume made his life away from boxing much easier, yet hovered over Chavez Jr. (46-0-1, 32 KOs) inside the ring. Arum thinks the pressure of honoring the Chavez name and the desire to establish his own strong legacy were factors in motivating him to improve enough to become a legitimate threat to Argentina’s Martinez (49-2-2, 28 KOs).

“The father’s image in Mexico completely overshadows any Mexican fighter, particularly his son,” said Arum, whose company, Top Rank Inc., brought the four-city press tour to its final stop Tuesday in Mexico City. “So that is why the kid has to prove his bones, in order to get out of that shadow. And the easiest way to do that is to take on the man everybody considers the best middleweight in the world, ‘mano a mano,’ and beat him.

“I think that if he wins this fight, he will do a lot, psychologically, to move out of his father’s shadow. And until [he took the Martinez fight], that wasn’t possible. Because you remember how everybody was referring a few years ago [to] how he was being protected and all that? Well, goddamn right he was being protected, because he didn’t know anything about professional boxing.”

Keith Idec covers boxing for The Record and Herald News, of Woodland Park, N.J., and BoxingScene.com.