The consensus opinion in boxing over the past several years has been that the best pound-for-pound fighter in the world was Floyd Mayweather, Jr.

Upon the announcement of Mayweather’s unexpected retirement, four-time world champion Manny Pacquiao was immediately anointed as his successor, a move made with minimal debate on most fronts. Yet this weekend welterweight champion Miguel Cotto could have something more to say about that and the louder he says it the better the chance that more than a victory will emerge from his confrontation with Antonio Margarito in Las Vegas.

A heated debate could also develop by Sunday morning if Cotto can defend the WBA title in spectacular fashion, a debate over a line of succession in the pound-for-pound weightless class that has stretched back from Mayweather through Shane Mosley, Oscar De La Hoya and Roy Jones, Jr.

For the past several years Cotto has been on most top 10 lists in that mythical category but he has seldom ascended much higher than fourth. RING magazine has even gone so far as to have him sixth, trailing not only Pacquiao but also Joe Calzaghe, Juan Manuel Marquez, Bernard Hopkins (huh?) and Israel Vazquez. Yet even though fighters have been listed above him, Cotto could prove this weekend that he is not only the best welterweight in the world but the best fighter in the world because he is facing the guy nobody would fight if they could avoid him.

Cotto could have done the same but chose not to, thereby proving a point by stepping in with Margarito and putting himself in position to prove a second one if he wins it. Cotto well understands this but it does not weigh on his mind as his date with Margarito approaches however because he knows his responsibility is to handle what he can handle, which he believes is the challenging Mexican who stands four inches taller and has a six-inch reach advantage. He cannot control the resolution of such theoretical debates as pound-for-pound champions and so has chosen not to concern himself with them, although not without making clear he thinks it will become a debatable issue by Sunday.

“I trained hard for 9 or 10 weeks to win and return to Puerto Rico with my belt,’’ Cotto said recently of the consequences of defeating Margarito in what is widely seen as the best welterweight match up that could be made.

“I had a really good camp and when I beat Margarito it is not up to myself to decide (who is the best pound-for-pound fighter). I will do my work in the ring the best I can.  The writers and the people who know about boxing who make those lists can answer that question.

“Everybody wants to see the best fighter go against the best fighter. I’m going to climb out of the ring on Saturday as a champion.”

If he does following the kind of fight most people anticipate this will be – which is one involving constant danger, stalking pressure and painful exchanges – then Miguel Cotto will have probably accomplished more than simply retaining his share of the welterweight title. He will have made a pronouncement about himself, one that began when he beat up Carlos Quintana to win the title and grew louder with his dominance of first Zab Judah and then Shane Mosley.

In many ways it was that latter victory that elevated him into consideration in the pound-for-pound debate because while Mosley is no longer the lightning quick champion he once was when he was considered the best fighter in the world he remains difficult to solve, fast and a quick-handed opponent who can stun you if you make a mistake.

In that fight, Cotto began to realize after a few rounds that his power alone would not allow him to dominate so he adjusted to the realities in front of him and began to box Mosley, ultimately outboxing the boxer to win both by the skillful use of tactics and the well-timed use of aggression and power.

That versatility is something Margarito lacks. It is also the kind of thing that separates the very best fighters in the world from the rest of the pack. Cotto has already done that. Now he has the opportunity to separate himself even from the Pac-Man himself.

Doing it, of course, will be complicated by Margarito’s size advantages, durable chin, pressuring style and ability to fight on the inside despite having arms six inches longer than Cotto’s. Those things make Margarito a stern test for Cotto but that of course is why, if he passes it, he must be elevated into any debate about who is the best fighter on the planet.

“The last two years for me have been wonderful,’’ Cotto said, referring to having left the struggles to make 140 pounds behind him. “All the people who know boxing saw another Miguel Cotto. A Miguel Cotto who can put pressure on opponents, but also a Miguel Cotto who can box, who can move.

“When you do those kind of things people know you are a complete fighter. That’s the kind of fighter they want to see.’’

Cotto is not simply a boxer, you see. He is a fighter desperate to prove where he fits in boxing’s hierarchy. That willingness to test himself in the hottest crucibles has become all too rare a commodity these days in a sport where champions pick and choose who they fight based more on avoiding challenges in favor of someone they feel provides the highest payday. In the best of circumstances, say like Mayweather vs. a blown up junior welterweight named Ricky Hatton, they get both.

Cotto has never taken that road. After Margarito won the IBF title last April by knocking Kermit Cintron stiff there was much agitating for the two to meet but Cotto held all the cards, especially after the unexpected retirement of Mayweather.

He was free to do what he wanted and there was little Margarito could do to force the issue but what Cotto wanted was exactly what boxing needed. He wanted to face the welterweight who posed the greatest risk to his future.

That man is clearly the long-limbed Mexican who is aggressive to a fault and so cocksure of himself he has promised a fourth round knockout. This week he reneged on that a bit, saying he was only fooling, but if he was it was a bad idea.

Accepting Margarito’s challenge was something Mayweather was accused of avoiding after he won welterweight titles from Judah and Carlos Baldomir and Cotto is well aware of that. When Mayweather unexpectedly retired some boxing insiders like Emanuel Steward theorized it might have in part been to avoid the growing demand to face the relentless and tactically sound Cotto (32-0, 26 KO) in a faceoff for welterweight superiority.

Contrast that with Cotto’s decisions to fight Judah and Mosley back-to-back after first winning the WBA title from Quintana and defending it against Oktay Urkal. If Cotto now defeats Margarito he will have beaten four of RING Magazine’s top five welterweights and three of’s top four (excluding himself from those ratings) in less than two years.

That may not make him the best pound-for-pound fighter in the world in the opinion of some but it won’t be easy to make an argument against him. That would be particularly true if he stops the iron-chinned challenger inside the distance, something that has never been done. It would be a statement of fistic supremacy few could quarrel with.

“I like Cotto,’’ former undisputed junior middleweight champion Winky Wright told the Puerto Rican newspaper Primera Hora recently. “He’s a very complete boxer. Margarito is a great puncher with size but Cotto can do a lot of things.

“He can box a lot more and he also hits hard so I expect to see Cotto leave with the victory. Cotto’s one of the best fighters out there. It’s difficult to say who is the best boxer in the world, pound-for-pound, but he’s one of them.’’

That list surely includes Pacquiao and Juan Manuel Marquez but beyond that who really is Cotto’s peer? Perhaps no one. Perhaps not even them.

“He’s a guy who always finds a way to win,’’ Steward said of Cotto. “We’ve never seen Floyd in the kind of adversity we’ve seen Cotto in and that’s not Floyd’s fault but what it tells you is that Cotto has a tremendous survival instinct.

“If things get too hot he can dance away and box. He can be a boxing machine if he has to be but if he has to be an aggressive fighting machine he can do that too.

“He can adjust to whatever he has to adjust to. Cotto fought the best guys at 140 pounds. He got knocked down. He was staggered. He was cut. But he found ways to win. He’s fought more of the top guys at 147 than anyone else with the same results. The guy endures. He beats you down. He is relentless in the way (Marvin) Hagler was relentless, and he damages you in the same way Hagler damaged people.’’

To have your name in the same sentence with Marvin Hagler says a lot about a man. If Miguel Cotto has his hand raised in victory again he will be a welterweight without peer. If it is raised at the expense of an unconscious or semi-conscious Antonio Margarito, he may be more than that. He may be a fighter without peer.