Juan Manuel Marquez says he has plenty left after Floyd Mayweather fight

Steve Marcus

Juan Manuel Marquez (left) takes a punch from Floyd Mayweather Jr. during a welterweight fight at MGM Grand Garden Arena on Sept. 19, 2009. Mayweather won the 12-round fight by unanimous decision.

By Brett Okamoto

Tuesday, July 20, 2010 | 11:30 p.m.

Juan Manuel Marquez was 19 years old when he made his professional boxing debut May 29, 1993.

More than 17 years later, Marquez still wakes in the early hours of the morning to run and put hours into the gym — and he's feeling better than ever doing it.

"It's not difficult at all to get up every morning," said Marquez on a conference call Tuesday. "I do it with the same enthusiasm I always have. I'm motivated to defend my titles with a lot of pride."

Marquez (50-5-1, 37 KO) will look to prove he's as good as ever July 31 in a WBO and WBA championship fight against Juan Diaz (35-3, 17 KO) at the Mandalay Bay Events Center.

The fight is a rematch of what many consider the 2009 Fight of the Year. Marquez won that fight via TKO in the ninth round.

Although Marquez, 36, still is considered by many as one of the top pound-for-pound fighters in the world, there is some concern on what he has left after enduring arguably the toughest two fights of his career.

Marquez absorbed a lot of shots from the volume-puncher Diaz in their first meeting and took even more damage in a one-sided decision loss to Floyd Mayweather Jr. in September.

Marquez said that he felt fine with the outcome of the Mayweather fight and that his struggles were magnified by the fact his opponent ignored the 144-pound weight limit.

"We knew going into the fight it would be a difficult task," Marquez said. "What made it even more difficult was the excess weight, approximately 15 pounds on the night of the fight, (Mayweather) had.

"During the fight, I felt good and we gave it our all."

Despite his struggles against a bigger Mayweather, a win over Diaz likely would have Marquez considering a permanent move up from the 135-pound lightweight division.

Should Marquez leave Las Vegas with a win, it could open the door to a fight with WBA junior welterweight champion Amir Khan.

If Marquez did claim a junior welterweight title, he would be the first boxer from Mexico to win world titles in four different weight classes.

"Right now, my mind is set for July 31 and on 135 pounds," Marquez said. "After the fight, we'll sit down and see what's next. Becoming the first Mexican fighter to win in four weight classes is something on my mind, but I'm 100 percent concentrated on July 31."

While his Mexican fan base likely would love to see Marquez make history, his trainer, Nacho Baristain, admits moving up would be a risky move for a fighter who has fought most of his career as a featherweight.

But even though it could be a challenge, Marquez has earned the right to try it with confidence.

"Juan is of a small physique," Baristain said. "For him to compete at higher weights is very difficult. Yet, I have to support him 100 percent in the ring because of his performances. The respect he's earned can not be denied, so I support him."

Even if Marquez is successful against Diaz and in claiming another world title, it's unlikely that will be enough to earn him what he truly wants before his career is over — a third meeting with WBO welterweight champion Manny Pacquiao.

The two fought to a draw in 2004 before Pacquiao took a narrow split decision in 2008. To this day, Marquez believes he won both fights.

Although Pacquiao and his representatives at Top Rank have shown no interest in a third fight, it hasn't stopped Marquez from hoping that somehow the fight will be made.

"Manny Pacquiao — that's my desire," Marquez said. "I want it so bad. I want that third fight with him before my career ends. Maybe other fighters would be Erik Morales or Ricky Hatton, but I want Manny Pacquiao for sure."

Brett Okamoto can be reached at 948-7817 or brett.okamoto@lasvegassun.com. Follow him on Twitter at LVSunFighting