The final chapter in Pacquiao-Marquez rivalry?

LAS VEGAS – Twenty four rounds, four knockdowns, two title fights.

It seems Manny Pacquiao and Juan Manuel Marquez can’t get enough of each other.

And so everything all boils down to this.

One of boxing’s most compelling rivalries adds a new chapter to its storied saga as Pacquiao and Marquez clash in the third installment of their bitter ring war Saturday night (Sunday, Manila time) before an expected sell-out crowd at the Grand Garden Arena of the MGM.

Seven years since their highly-disputed first meeting, and three years after a debatable rematch, the two great warriors hope to finally  end  a feud that has become too personal for comfort, going at each other again like madmen for another 12 full rounds, but this time for the World Boxing Organization (WBO) welterweight title belt being fought at a catch weight of 144 lbs.

Assured of a guaranteed purse of $22 million, Pacquiao is a 9-1 heavy favorite to beat Marquez, who’s getting a $5 million paycheck, the biggest of his  career.

Pacquiao, the reigning champion, maintained he has nothing more to prove, but found himself meeting his Mexican challenger for a third time to end all doubts that haunted their two previous battles.

“I have to end all the issues, all the doubts in people’s minds about me beating him,” said the 32-year-old pride of the Philippines, where he’s also a duly-elected congressman.

But for Marquez, this could yet be the opening he’s been waiting a long time to make a case that he truly won their 2004 and 2008 bouts.

“Our goal was to get him to give us a third fight,” said Marquez, who previously worked as an accountant until going into boxing full-time in 2000. "And here we are.”

“This third fight will show who’s the best.”

Who’s the best was not exactly answered the first time the two rivals met, their title match for the World Boxing Association (WBA) and International Boxing Federation (IBF) featherweight belts ending up in a controversial draw despite Pacquiao scoring three sensational knockdowns in the opening round.

In their rematch four years later for the World Boxing Council (WBC) super-featherweight crown, the `Pacman’ sent Marquez to the canvas in the third round, ultimately spelling the difference in a 12-round split decision in favor of the world’s top pound-for-pound fighter.

Marquez, however,   believed he won both fights, at one time even wearing a shirt with the words `Marquez Beat Pacquiao Twice’ printed on it, and didn’t stop trying to prove his point, until finally landing a third shot against his long-time rival in a fight he thinks he truly deserved.

And so he tapped a strength and conditioning coach in Angel Heredia, added muscles, and bulked up to meet Pacquiao in a weight class the country’s beloved son has thoroughly dominated since brutally sending the great Oscar De La Hoya into retirement in 2008.

“I am ready for this fight, which is the most important in my career,” declared Marquez shortly after tipping the scales at 142 lbs. during Friday’s official weigh-in at the MGM Garden Arena before a crowd of 6,000.

“I want to fight the best pound-for-pound fighter in the world, and I need to win every round clearly,” said the 38-year-old challenger from Mexico City, owner of a 53-5-1 record, including 39 KOs.

Pacquiao, whose ring record stands at 53-3-2, including 38 KOs, came a pound heavier at 143 in his third defense of the WBO championship he won from Miguel Cotto in 2009.

“I have to do my best in the ring because I don’t want them (fans) to be disappointed,” said the boxing superstar who once sold bread in the streets of General Santos City as a youngster.

“I’ll just rest (after this) and prepare for the battle tomorrow (today).”

Marquez came in at the exact weight he did in his first foray as a welterweight two years ago, when he looked very slow and sluggish in a lopsided decision against Floyd Mayweather Jr.

In contrast, Pacquiao has been destroying just about the best fighters there are in the 147-lbs division, from De La Hoya, Ricky Hatton, Cotto, Joshua Clottey, Sugar Shane Mosley, to the giant Antonio Margarito.

Those impressive victories are part of a 14-fight winning streak the deadly Filipino southpaw carries with him in a six-year span, with Mexican Erik Morales the last fighter to deal Pacquiao a defeat inside the ring in 2005.