Manny Pacquiao and Juan Manuel Marquez bout for the WBO Welter Weight Title… (Jewel Samad / Getty Images )
LAS VEGAS -- Manny Pacquiao will smile his way to the ring Saturday night. His opponent, Juan Manuel Marquez, will glare.
Pacquiao will try to beat his Mexican rival for the third time in four fights by again throwing caution to the wind with flurries of punches.
Marquez will again be more calculating. Convinced he's the smarter of the two in the ring, he has strengthened his body as never before at age 39, hell-bent to impose his will and finally have his hand raised in victory against Pacquiao after suffering two agonizingly close decision losses and a draw.
"This fight is more important than the last three," Marquez said of Saturday's non-title welterweight bout at the MGM Grand in Las Vegas. "Because it's for my legacy. The honor. The pride.
"For everything," Marquez said.
In this rivalry, those words are as fiercely serious as the hard stare Marquez delivers.
Remember, in 2004, Marquez was knocked down by Pacquiao three times in the first round, scraped himself up each time and rallied to win nearly every other round to gain a draw.
Their 2008 battle was incredibly narrow, Pacquiao winning a split decision because of an early knockdown. And their November 2011 classic was met by a roar of boos when Pacquiao was declared the winner by majority decision.
Marquez insisted this week that his career will not be defined by the Pacquiao fights.
Who's he kidding?
Sports history is loaded with greats best remembered for losing to their foil, or falling short of clutching the brass ring.
Joe Frazier lost two of his three fights with Muhammad Ali. The Lakers' Jerry West was a tragic hero when his team lost six NBA Finals to the Boston Celtics' dynasty in the 1960s. Charles Barkley, Dan Marino and Barry Bonds are others who come to mind.
Is the die cast for Marquez? Or can he alter the story?
Marquez undoubtedly has turned over every stone to search for the way to finally defeat Pacquiao, which explains his controversial union with strength and conditioning coach Angel "Memo" Heredia.
Earlier in his career, Heredia was a steroid supplier to track stars Marion Jones, Justin Gatlin and Tim Montgomery, then became a government informant in the prosecution's case against track coach Trevor Graham.
Marquez and Heredia say that the boxer's new muscular build came about naturally in training. Heredia called Marquez "Hulk" at Wednesday's news conference.
"Anyone who wants to test me, I invite him to have spent the last four months with me, to have got up at 4 a.m. with me every day, do the eight hours of work, and then tell me whether I'm doing this naturally or not," Marquez said.
Marquez's weightlifting regimen in Mexico City and his conditioning in the mountains, at 14,000 feet above sea level, have brought him to peak shape before his fourth bout against Pacquiao, said Marquez's veteran trainer, Ignacio "Nacho" Beristain.
Marquez can't wait to unload his mighty left uppercut on Pacquiao, Heredia said.
"Pacquiao is a guy who's as difficult to knock down as a tree trunk," Heredia said. "Last fight, Juan hit him so hard he fell back a meter. We want to hit him again like that and see what happens.
"And Pacquiao hits hard, with those snappy and strong punches. There's solid strength and speed strength, and we have both now."
Beristain added, "My fighter's a lot smarter than Pacquiao, and a superior technical fighter."
The betting public anticipates another close brawl. Last year, Pacquiao was an 8-to-1 favorite at Las Vegas sports books. On Thursday, MGM Resorts listed Pacquiao at less than a 3-to-1 favorite.
Pacquiao's trainer, Freddie Roach, doesn't expect Marquez to change, not after 61 pro fights: "He's a counterpuncher through and through. I wish he'd be more aggressive like he's saying. I don't think it'll happen," Roach said.
"We'll remain the aggressor, and aggressors, as we've shown, win close rounds. I want Manny fighting all three minutes of every round. With more action, there'll be no question who the better man is."
Fueled by disappointment that has amplified with each Pacquiao fight — Marquez believes he won all three — the Mexican fighter said he converted his rage into his preparations for this fight.
"My highest motivation is wanting to have my hand raised," Marquez said. "I don't want to live with people telling me, 'We thought you won.' I want to really know I won."
Pacquiao said a major reason he wanted a fourth Marquez fight is to quiet his adversary, once and for all, to settle how each fighter will be remembered.
"He doesn't respect the decisions of the judges, so he needs to prove something Saturday," Pacquiao said. "But we expect to be more aggressive than ever, and I'm better prepared for the battle when it happens. I'm faster than him.
"It's not about the size. It's about the speed."
Right now, that's the epitaph. Marquez has one last chance to pound in new words.