LAS VEGAS » Just the idea of a big 160-pound fight had promoter Bob Arum reminiscing about the 1980s, when Marvelous Marvin Hagler and Thomas Hearns took on all comers and middleweights ruled the boxing world.

Tonight’s fight between Julio Cesar Chavez Jr. and Sergio Martinez isn’t exactly Hagler-Hearns, but it is intriguing enough to get boxing fans excited about the middleweight division again.

Chavez defends the piece of the 160-pound title Martinez believes should still be his when they meet in a fight that seems quite personal to both. There’s a good chance the fight could turn into an old-fashioned brawl, the prospect of which was enough to sell out the 19,000-seat UNLV campus arena for the Mexican Independence Day weekend bout.

Chavez Jr. is fighting to escape from the shadow of his father, the legendary Julio Cesar Chavez, and establish himself as one of the new stars of the sport. Martinez is trying to solidify his position as the best middleweight in the world, and dispatch a fighter he doesn’t think even deserves to be in a title fight.

At the final pre-fight news conference, they traded verbal shots, with Martinez about as angry about an opponent as any fighter can get.

“It will not be an easy knockout,” Martinez said. “I will punish him a lot and after that I will knock him out.”

Martinez is a 2-1 favorite in the scheduled 12-round bout, which will be for the WBC title that Martinez held before being stripped of it by the ratings organization. Chavez ended up fighting for the vacated title against Sebastian Zbik, part of the reason Martinez says he has a lot of animosity toward him.

“It is very simple. I cannot accept the fact he is world champion,” Martinez said. “The only reason he is world champion is because he is Julio Cesar Chavez Jr., the son of the legend, and his mouth is so big — even bigger than his own brain — and he’s talking too much.”

The fight is part of a big boxing night in this gambling city that also features Mexican sensation Saul “Canelo” Alvarez in a 154-pound title defense against Josesito Lopez a few blocks away at the MGM Grand hotel. The Chavez-Martinez fight will be broadcast on HBO pay-per-view at a suggested price of $49.95, while the Alvarez fight will be broadcast without an extra charge on Showtime.

Chavez, who has struggled in recent fights trying to make the 160-pound limit, was a surprisingly light 158 pounds at the official weigh-in Friday. Martinez came in at 159 pounds.

Aside from their obvious dislike for each other, the fight between Chavez and Martinez offers some other good storylines.

Martinez is a late bloomer, a 37-year-old Argentine who in recent years has fought his way to the top of the middleweight division. He’s a lefty with a style that’s hard to counter, though his chin his questionable and he has been on the canvas in some of his fights.

Chavez is taller and figures to outweigh Martinez on fight night after struggling to make the 160-pound weight limit. He’s a big puncher who has come into his own in the last couple of years after being brought along very slowly by matchmakers who liked his determination but weren’t sure he had the skills to become a top fighter.

Now he brings an unbeaten record of 46-0-1 into the fight and has become such an attraction to Mexican fans that the fight sold out nearly a week early.

“In the last two years he’s demonstrated to everyone he’s capable,” Arum said. “There’s a lot of big things ahead if Julio is successful in this fight. We think he’ll become one of the biggest attractions in boxing, on the level of a (Manny) Pacquiao or (Floyd) Mayweather.”

Chavez is coming off perhaps his best performance, stopping a tough Andy Lee in the seventh round June 16 to defend his title. Chavez trailed early in that fight but came on strong and dominated Lee physically before finally stopping him.

“He hadn’t had a lot of experience with southpaws and he fought that fight great,” trainer Freddie Roach said. “After that fight we knew it was time to step up. We knew Martinez was a southpaw. We know how to fight a southpaw now and his father and I have been coming up with a game plan.”

Part of that game plan was getting Chavez to the gym, something that proved difficult as documented in the HBO “24/7” prefight series. Roach was left waiting at the gym several times, but says Chavez eventually put in enough work to get him in shape for Martinez.

“I had to wait in the gym for him a few times, but for a world champion I will wait,” Roach said.

Chavez is guaranteed $3 million for the fight, while Martinez is getting $1.4 million plus a portion of the pay-per-view. The payout reflects the popularity of Chavez, though Martinez wanted the fight so badly he said he is not troubled by being paid less money than his relatively unproven opponent.

“Chavez will get more money,” he said, “but he’s going to get more of a beating, too.”