MERIDIAN —

    LAS VEGAS  — The fact they're much bigger than when they first met eight years ago is undeniable. Both Manny Pacquiao and Juan Manuel Marquez have added bulk along with the pounds, and both have had to deal with those who suspect they didn't do it naturally.

    The fighters aren't the only thing that's grown. So have the purses and the attention as they meet Saturday night for the fourth — and presumably last — time in the rivalry that has served both fighters so well.

    Marquez will try once again to do what he hasn't been able to do in 36 evenly contested rounds against Pacquiao — get a decision from the ringside scorecards. At the age of 39, it's a fight that may mean more to his legacy than his future career, which is why it's a fight he seems almost desperate to win.

    "All I ask is for the judges to be objective," Marquez said. "They need to really see what is happening in the ring instead of what they think might be happening in the ring."

    Pacquiao is not as desperate, but he needs a win just as badly. He barely escaped with a majority decision over Marquez last November — a result that drew loud boos from the pro-Marquez crowd — and lost a widely panned decision to Timothy Bradley his last time out.

    A loss to Marquez would not only confirm the whispers that he is slipping after 17 years as a pro, but perhaps derail for good any talk of a fight against Floyd Mayweather Jr. that would be boxing's richest ever.

    "I have always been focused, but not like this fight," Pacquiao said. "There are no distractions in my mind. The family problems I had I don't have this time."

    Neither fighter holds a title as they meet in a welterweight fight that will make both even richer. Pacquiao is expected to make more than $20 million by the time the pay-per-view receipts are totaled, while promoter Bob Arum said Marquez could make as much as $6 million.

    It's a far cry from 2004, when Pacquiao and Marquez could barely fill half the arena, and the money they made would barely pay for one of their luxury cars today. The fight, though, was plenty intriguing, with Pacquiao coming off a win over Marco Antonio Barrera that announced his entry into boxing's elite and Marquez having stopped his last 11 opponents.

    It seemed a mismatch when Pacquiao knocked his fellow 125-pounder down three times in the first round and Marquez barely survived to hear the bell. But the Mexican champion began a comeback in round 3, dominating the late rounds on his way to a disputed draw that foreshadowed what was to come in the years ahead.

    All three fights — Pacquiao won the last two — were so close they could have gone either way. And had they gone the other way, boxing history may have changed.

    Pacquiao might not have gotten the fight with Oscar De La Hoya that catapulted him to stardom in 2008 just nine months after beating Marquez in a split decision in their second fight. Marquez, meanwhile, might have become more than just an opponent getting rich off the names of fighters who will be judged better than him.

    "My career maybe changed, and everything would be different," Marquez said. "But I feel great what happened in the past with Manny."

    A fourth fight between two world class fighters is almost unheard of in a day when top fighters rarely enter the ring more than twice a year. Almost as astonishing is that they were spread out over eight years and five weight classes, yet Saturday night's fight will still be a pay-per-view event that will likely draw more than 1 million buys (HBO $59.95) across the country.

    If the old rules of boxing applied, Pacquiao would be fighting a rematch with Bradley for the welterweight title he lost in June in what most watching thought was one of the worst decisions in recent years. But Bradley doesn't sell pay-per-views and Marquez does, so he's on the sidelines as Pacquiao and the Mexican opponent he knows so well battle for riches instead of a crown.

    As is the norm in the sport, the fight needs some controversy to sell. This time it's about Marquez bulking up in ways a 39-year-old normally can't and the ties his strength coach has to steroid scandals of the past.

    Angel Guillermo "Memo" Heredia provided track athletes like Marion Jones and Justin Gatlin with steroids and human growth hormone, only to escape prosecution in the BALCO case by agreeing to testify for the prosecution. He hotly denies using anything with Marquez, claiming his fighter has bulked up only because of an unorthodox strength and conditioning program he designed for him.

    Pacquiao's trainer, Freddie Roach, said Marquez didn't look like a fighter who had naturally grown, prompting a threat of a lawsuit by Heredia and denials by Marquez himself.

    "You can say anything you want but you have no proof," Marquez said. "Let's go together and I'll do any test you want."

    Pacquiao, who himself was the target of suggestions by Mayweather's camp that he used something to grow, said he wasn't worried about it.

    "Let's give him credit for hard work," Pacquiao said. "It's not about size, it's about how you function in the ring. I've been fighting bigger guys all my life."