No world title is at stake, but nobody seems to care as archrivals Manny Pacquiao and Juan Manuel Marquez head to their fourth meeting on Sunday (Manila time) at the MGM Grand Garden Arena in Las Vegas, Nevada.

Together, Pacquiao and Marquez have won a total of 12 world boxing championships, eight for the Filipino and four for the Mexican.

Their three previous meetings have all been for a world title. In May 2004, Pacquiao and Marquez battled to a draw, allowing Marquez to retain the World Boxing Association (WBA) and International Boxing Federation (IBF) featherweight (126 pounds) titles.

Four years later, on March 15, 2008, Marquez lost his World Boxing Council (WBC) lightweight (135 pounds) crown to Pacquiao on a disputed split-decision.

In their third meeting on November 12, 2011, Pacquiao barely retained his World Boxing Organization (WBO) welterweight (147 pounds) diadem with a majority decision victory.

With enough world titles to plug the gaping holes on the ozone layer, the fourth meeting between Pacquiao and Marquez is all about bringing to a conclusive end their epic rivalry. For the record, Pacquiao is 2-0 with 1 draw against Marquez, but considering the controversial ending of all three fights, not a few boxing observers believe that the fighters are back to square one going to their fourth showdown, with neither enjoying a distinct advantage. Believe it or not, in the 36 rounds the fighters have figured in, there have been only 3 rounds where one outpunched the other by at least 10 blows.

“It’s very, very important [for me to get a victory in this fight],” said Marquez, who totes a record of 54-6 with 39 knockouts. “I have this opportunity and the victory will be mine and I will be able to retire with a victory over Pacquiao.”

“I am giving him a chance to prove he can win the fight because he thought he has won all three and he keeps talking about it,” countered Pacquiao, 54-4 with 38 knockouts. “So it is very important for me to win this fight.”

Pacquiao and Marquez are so familiar with each other’s styles that many expect the fourth fight to follow the same pattern as the last two. Oozing with young blood and bravado, the first meeting provided unbelievable thrill and chill, with Pacquiao scoring three knockdowns in the first round and Marquez rallying to salvage a stalemate. The last two fights, however, have been relatively tame, with the fighters arguably showing too much respect for each other.

Pacquiao and Marquez are both promising to drop their fistic inhibitions for their fourth matchup.

“I always train hard, but this time a little harder,” said Pacquiao. “Harder and more punches, and some changes. We have been throwing more combinations and changing our strategy—in movement. So it will be a little different than the last one.”

Experts agree that Pacquiao will have to go regain his old, whirlwind offense if he is to finally silence Marquez. During his younger days, when he was solely focused on boxing, Pacquiao was a phenomenal punching machine. Feverishly embracing religion and embarking on a political career, Pacquiao has noticeably become soft in his last few fights, ultimately leading to the unexpected loss to Bradley. Trainer Freddie Roach, however, considers Pacquiao’s problem more mental than physical.

“His focus is where it has not been for some time,” admitted trainer Freddie Roach. “He is very focused for this fight and I think it’s going to be the best fight yet.”

Marquez, 39, is looking to step out of his counterpunching cocoon and go for the jugular, too. Marquez has considerably bulked up for the fourth fight, believing that he needs to be physically strong in the event the going gets tough on the inside.

“I am going to be aggressive in this fight,” said Marquez. “I won’t go for the knockout right away but if I get the opportunity for the knockout, I will go for one.”

If the fighters live up to their promise, their fourth collision might just shape up as the most exciting yet. Pacquiao remains the odds-on favorite, but Marquez is breathing down his neck and is a live underdog. Make no mistake, when it is the legacy of the fighters that is at stake and not another crappy world title, expect nothing less than a never-say-die approach from them.

“It will be a fight that will go into the annals of boxing history because these gentlemen that fought three previous times and over the course of the timeline, this fourth fight will be the best fight of all,” trumpeted promoter Bob Arum.