LOS ANGELES – Juan Manuel Marquez’s task was difficult enough.

The six-time titleholder from Mexico will be facing the quickest, slickest fighter in the world when he steps into the ring with Floyd Mayweather Jr. on July 18 in Las Vegas. And he’s moving up two weight classes to do it.

At least the fighters appeared to agree on a catch weight of 144 pounds, as it was explained by Marquez’s camp when the fight was announced on May 2.

However, now, even that equalizer is gone. The sides have agreed in the end that this will be a welterweight fight, meaning they can weigh as much as 147 pounds. That’s exactly what Mayweather weighed in his last fight, against Ricky Hatton in December 2007.

It’s no wonder the former pound-for-pound king is better than a 3¾-1 favorite.

Marquez acknowledged during a news conference Monday in downtown L.A. that, “this is not my weight,” but said he’s doing all he can to minimize what would seem to be a significant advantage for Mayweather.

He’s training in the mountains of Toluca, Mexico.

“We’re doing a lot of strength training,” he said through a translator, “building my body, building muscle. We’re working out, believe it or not, lifting heavy rocks. We’re just trying to get my body ready for this fight.

“ÔǪ I’m confident I’ll be able to match him (in terms of strength).”

Marquez, THE RING’s No. 2-rated fighter pound for pound, knows that the experts favor Mayweather and acknowledges that the size is only one obstacle he’ll have to overcome if hopes to win.

However, the 35-year-old veteran who fought on even terms in two fights with Manny Pacquiao and appears to be better than ever is confident that he’ll do what it takes to score the biggest victory of his career.

“People have a right to say whatever they want,” he said. “That’s what’s motivating me right now. I’m confident, confident in my preparation, in the game plan, in what I’ll need to do in the fight. It motivates me to shut their mouths.”

Marquez has another motivating factor: The chance to become a true star in Mexico.

Mexican fighters have had a tough time recently. For example, Marco Antonio Barrera and Erik Morales declined and now appear to be finished. Antonio Margarito was KO’d by Shane Mosley and then suspended because of illegal hand wraps. And flyweights Cristian Mijares and Jorge Arce suffered big losses.

Clearly, Marquez, coming off sensational knockout victories over Joel Casamayor and Juan Diaz, is the top dog right now but he’d like to take it a step further.

“I have a great chance to be the next idol in Mexico,” he said.

All he has to do is score the upset.

Payback: Mayweather said Marquez deserved this opportunity in part because another fighter with Mexican blood once gave him a chance.

Mayweather was 21 years old and 17-0 when Mexican-American Genaro Hernandez, one of the most-polished boxers of his time, agreed to risk his WBC junior lightweight title against the hot young prospect. It was Mayweather’s first shot at a major belt, which he won when an overmatched Hernandez retired after the eighth round.

Mayweather became the first member of the 1996 U.S. Olympic team to win a world title.

“Genaro Hernandez gave me a big chance; I have to give (Marquez) a chance,” he said. “And I want to say that I know Genaro is sick. I want him to know I’m here if he needs anything. We all just want him to get well.”

Hernandez has been battling cancer but is in the early stages of remission.

Mosley?: Those hoping for a Mayweather-Shane Mosley fight shouldn’t hold their breaths. Mayweather doesn’t seem to be interested.

Mayweather said he wanted to fight the Los Angeles-area product around the time of the Hernandez bout, when Mosley held a lightweight title, but Mosley wasn’t interested. Now, it seems to be too late. He said he can make more money against other opponents.

“Now that he has five losses and his career is coming to an end, he wants to fight,” Mayweather said. “No disrespect to him but Mosley can only sell tickets in L.A., in California. I’m not saying he’s not a good fighter; he is. When you’re talking pay-per-view, though, he doesn’t do tremendous numbers.”

Mayweather-Mosley wouldn’t do as well as Mayweather-Marquez in the United States?

“Absolutely not,” he said.

Leonard Ellerbe, Mayweather’s advisor, then chimed in: “When has Shane Mosley ever been the “A” side of a promotion? That’s all I have to say.”

Family matters: Mayweather said one of the benefits of his hiatus from boxing, which will be 19 months when he steps into the ring on July 18, was that he had the opportunity to spend time with his family.

That didn’t include his estranged father, trainer and former boxer Floyd Mayweather Sr. However, he obviously has respect for the old man.

“He’s been to prison,” said Mayweather Jr., referring to his father’s five-year term for drug trafficking in the mid-’90s. “He went out there and hustled, took a big chance to feed his family when boxing didn’t work out for him. Boxing happened to work out for me. My dad put it all on the line so his son could have a better life.

“ÔǪ For him to be in prison for five years and come back to be one of the best trainers, I have to take my hat off to him.”

Michael Rosenthal can be reached at [email protected]