Manny “PacMan” Pacquiao promises to rekindle his explosive aggressiveness and go for a knockout when he takes on arch-rival Juan Manuel Marquez of Mexico on Saturday night (Sunday in Manila) in a crucial fourth fight of what is probably the greatest ring rivalry in the world today.

Pacquiao, who turns 34 on December 17, is a 3-1 favorite to repeat his mastery over Marquez, the legendary Mexican champion in four-weight division and the only elite fighter to have pushed Pacquiao to the limit in three previous close fights.

No title is at stake in this fight, but both Pacquiao and Marquez believe they carry on their shoulder the honor and pride of their boxing-crazy countries, the Philippines and Mexico.

A man of few words, Pacquiao told a small group of Pinoy journalist that Marquez’ boxing career will have its “expiry date” on fight night and vowed to win convincingly “to erase all doubts in the mind of the fans” about the controversial results of their past fights.

Pacquiao and Marquez first fought as featherweights in May 2004 which ended in a disputed split draw. Almost four years later, Pacquiao snatched Marquez’ World Boxing Council super featherweight title by split decision and defended his World Boxing Organization welterweight belt by majority draw in November 2011

Emphasis on speed
Pacquiao, the only fighter to win world titles in eight different weight classes, said his nearly six weeks of training at his American trainer Freddie Roach’s Wild Card Gym in West Hollywood stressed hand speed, greater movement and throwing combinations in bunches—the key ingredients of Pacman’s attacking game.

“What we are doing every day is more intense than the last few fights,” said Pacquiao on HBO’s 24/7, who emerged from his closed-door US training leaner, quicker and more agile than his previous training camps.

Pacquiao said that he feels good and is 100 percent ready for whatever Marquez brings to the ring.

His renowned trainer, Freddie Roach, said that his prize Filipino fighter trained hard and well and has urged Pacman to knockout Marquez to shut him up.

Bigger, stronger Marquez
In contrast, Marquez, the reigning WBO light welterweight champ, comes to the fight visibly bigger and muscled than in previous fights, the result of at least three months of rigorous training aimed at improving Marquez’ strength and speed with the help of controversial conditioning coach Angel Hernandez.

Like a broken record, Marquez insists that he has won all his previous scraps with Pacquiao and that he would do his best to take the verdict out of the judges’ hands.

“I focused in everything [for this fight]—in speed, in strength,” Marquez, 39, told ABS-CBN news. “I want to win this fight by knockout.”

In another interview, Marquez admitted he “needs to change something” in his game plan and he needs to do “something different.”

His great Mexican trainer, Ignacio “Nacho” Beristain said that Marquez has to be “more aggressive without being careless” against a dangerous opponent like Pacquiao.

Hernandez, the conditioning expert, said Marquez trained hard and long, working on speed, stamina and power.

“We trained very hard for this fight. It was a longer preparation and we feel pretty comfortable,” said Hernandez, who admitted to US authorities providing several American track and field athletes with performance-enhancing drugs in the past.

Hernandez said the best way to deal with Pacquiao’s vaunted power and explosiveness is for Marquez to use the same speed and power against him.

“If we compare last year, it was a camp where he didn’t do a lot of exercises,” Hernandez said. “[This time] we were able to perform more exercises, more dynamics right to the point. So, he’ll be sharp.”

No clear winner
Veteran boxing commentator Larry Merchant said he is intrigued by the unpredictability of the Pacquiao-Marquez 4, a fight between two evenly matched elite boxers who have fought a total of 36 rounds with no clear-cut winner.

“The excitement of this fight is that either Pacquiao or Marquez is capable of beating each other,” Merchant said in an interview.

Merchant said that it would be interesting to find out if Pacquiao could summon the same the electrifying energy that enabled him to conquer bigger opponents like Oscar de la Hoya and Miguel Cotto and Shane Mosley and which brought him to the pinnacle of ring success.

Merchant, who will team up with HBO’s Jim Lampley in the televised pay-per-view fight coverage, said that the fans want to find out if the counter-punching genius in Marquez would be “willing to take risks” against Pacquiao who usually impress the judges in close rounds because of his attacking style.

A must-win
Although he hardly completed the usual eight weeks in training camp, Pacquiao said he feels very sharp and strong for a fight he needs to win to keep his top pound-for-pound standing and shore up image following less than impressive performance in his last few fights.

An upset by Marquez would minimize Pacquiao’s options for a few more big-ticket fights before retiring, including a potential mega fight with Floyd Mayweather Jr. in the second half of 2013.

Although showing signs of decline Pacquiao indicated that he is not quite ready to hang his gloves, win or lose, after his fourth encounter with Marquez.

Pacquiao told newsmen on Tuesday he is open to taking on young slugger Brandon Rios or even a rematch with Bradley should the huge fight with Mayweather fail to fan out next year.

A Marquez victory will secure the Mexican legend’s legacy as the great Mexican fighter to finally stop Pacquiao’s domination over some of the very best Mexican fighters of this generation.

It will also pave the way for at least a few more big-money paydays for Marquez, including a fifth tussle with his Filipino arch-rival.

Fight predictions
In a poll by RingTV.com of 27 boxing experts—sportswriters, trainers and boxers—those polled chose Pacquiao 2-1 over Marquez in yet again another close contest.

The experts’ opinion somehow reflect a similar bias among Las Vegas bookmakers who had Pacquiao a 3-1 favorite, which is a marked improvement from the 7-1 odds in their third fight in November 2011.

Few of experts or even fans are buying the hype that both Pacquiao and Marquez are going for a knockout.

In his prime, Pacquiao was unable to stop Marquez after 36 rounds and there is no reason to believe that a slightly declining Pacman could do the trick this time. He failed to finish off Marquez despite three knockdowns in the opening round of their first fight in 2004.

It is even more inconceivable for Marquez, who has never seriously hurt Pacquiao in three fights, to stop or even knock Pacquiao down on fight night.

Should there be a knockout, the likelihood is that Pacquiao, who his trainer reported flooring sparring mates at least four time in training, will be the likely author of the KO.

This writer sees the fight going to the scorecards yet again in a tough back and forth slugfest that could go either way.

As in the previous fights, Pacquiao will start strong and seek to dictate tempo in the early rounds. He will explore opportunities for an easy win as he promised, but he won’t force the issue at the risk exposing himself and being hurt by the Mexican dynamite.

With his superior conditioning, Marquez will rally in the middle rounds and even try to take risks to impress the judges to secure the win in the late rounds.