What is Mayweather's zero worth?

You could still see flashes of greatness as Sugar Ray Robinson fought his final fight -- a feint here, a pivot there, an occasional well-placed jab. But on that chilly November night in 1965, greatness flickered like an ember among the ashes of his 200-fight career, just a melancholy reminder of the beacon that once illuminated the boxing world with dazzling brilliance.

The crowd that gathered at Pittsburgh's Civic Arena to watch a living legend make his last stand gave Robinson several standing ovations. The fact that middleweight contender Joey Archer knocked the old champ down and won the decision didn't detract from Robinson's legacy one iota. It was his 19th defeat -- an unacceptable number by today's standards -- but almost a half-century later, the original Sugar Ray remains the consensus choice as the greatest fighter to ever grace a boxing ring.

Not everybody agrees with that opinion, of course. Muhammad Ali also gets a lot of support. Among the most vocal dissenters is Floyd Mayweather Jr., who believes it is he, not Robinson or Ali, who deserves to sit atop boxing's Mount Olympus.

"I got respect for Sugar Ray Robinson. I got respect for Muhammad Ali," Mayweather, who faces Robert Guerrero on Saturday at the MGM Grand in Las Vegas, said. "But I'm a man just like them and put on my pants just like they put on their pants. What makes them any better than me?"

Although you'll never convince Mayweather, who holds his undefeated record close to his heart, it was, in part, the losses that Robinson and Ali suffered and their ability to overcome adversity that set them apart. On some level, Floyd must know that stats alone are not the true mark of greatness, but he always falls back on his unblemished career mark when questioned about his self-proclaimed status.

"Numbers don't lie," Mayweather insisted in a recent interview with ESPN's Stephen A. Smith, who reminded the fighter that his claim to be "the best ever" was not universally accepted.

Numbers might not lie, but they sure can be misleading. As much as Mayweather cherishes the zero at the end of his 43-0 (26 KOs) record, even if he remains unbeaten for the remainder of his career, which is entirely possible, he wouldn't be unique in that distinction -- not by a long shot.

Undoubtedly the most celebrated member of Club Zero is former heavyweight champ Rocky Marciano, still a cult hero close to 58 years after the final fight of his 49-0 (43 KOs) career. Nowhere near as famous as the "Brockton Blockbuster" (but arguably a better fighter, pound for pound) is Ricardo Lopez, Mexico's breathtakingly gifted strawweight king, who finished his career with a 51-0-1 (38 KOs) record. The pair resides on a lofty plateau, high above the others who retired undefeated. A notch below are the likes of Joe Calzaghe, Lazlo Papp, and Jimmy Barry, all highly accomplished fighters without a loss between them but who aren't in quite the same league as Marciano and Lopez.

Then there's Saengmuangnoi Lukchapormasak, better know as Samson Dutch Boy Gym, who retired with a glossy 43-0 (36 KOs) record, including no fewer than a staggering 38 title defenses. The Thai junior bantam sounds like a shoo-in for the Hall of Fame with those sorts of stats, but when you examine his record, you discover he held the lightly regarded World Boxing Federation title and, with only a few exceptions, fought mainly obscure opponents of little merit.

If numbers are just the starting point in the evaluation of a fighter's legacy, why is Mayweather fixated on the almighty zero? Is it a way to reassure himself that he's really as good as he says he is, a salve to sooth the slings and arrows of his critics -- or something else altogether?

Part of the equation is the current boxing culture, which is almost as obsessed with undefeated records as Mayweather is. It wasn't always that way, of course, and throughout most of boxing history, as long as it was a good fight, a loss wasn't that big of a deal. True, boxers fought more frequently in those days, mainly because purses were relatively small compared to today, but a busy schedule also made it easier to move on after a defeat.

Another factor in the contemporary emphasis on undefeated records is the runaway proliferation of alphabet groups and the downgrading of the titles that has resulted from their innumerable transgressions. In an era inundated with so-called champions, the term has lost much of its significance, making a pristine record and a lofty P4P (pound for pound) rating of more consequence than ever before.

Even so, it would be wrong to consider Mayweather a captive of the times in which he fights. He is instead a prisoner of his colossal but surprisingly fragile ego, the part of him that is both his greatest strength and most glaring weakness.

Mayweather's mercurial personality is as difficult to pin down as the fighter himself is inside a boxing ring. The villainous persona that has helped make him today's top pay-per-view attraction doesn't really represent who Floyd is -- no more than Guerrero's conspicuous religiosity characterizes him.

Sure, Mayweather went to jail on a domestic violence beef, but he blew any street cred that incarceration might have earned him by whining about the lack of bottled water. Guerrero's appearance on "The 700 Club" with Pat Robertson, founder and chairman of the Christian Broadcasting Network, was closely followed by "The Ghost's" arrest for packing heat at New York's John F. Kennedy Airport.

The black hat-versus-white hat dynamic doesn't apply this time. It seldom does, and any analysis of what makes either Mayweather or Guerrero tick is all about shades of gray.

Mayweather's critics believe he has grown more and more cautionary in the selection of opponents as he has climbed the P4P ratings. They point to matches with shell-shocked Arturo Gatti, shopworn Shane Mosley and undersized Juan Manuel Marquez as prime examples. Then there were outclassed foes such as Victoriano Sosa, DeMarcus Corely and Carlos Baldomir whom he allowed to last the distance, rather than risk something untoward by going for a knockout.

"What [the fans] really want to see is me get my ass kicked," Mayweather said during a candid moment at an after-party following his victory over Mosley.

Although there is certainly a sizable segment of boxing's fan base that feels that way, it should not be forgotten that Mayweather is the first black fighter since the fall of Mike Tyson to attract a large and loyal African-American following. Moreover, the social-media war between his fans and Manny Pacquiao supporters suggests that Mayweather's brand of bravado, backed up by his marvelous boxing ability, has won favor with many.

According to self-help blogger M. Farouk Radwan, "The psychology of people who strive for perfection is easy to understand. You just need to look at the direction they are running towards and you will have a powerful clue about the direction they are running from."

Todd duBoef, president of Top Rank Boxing, recalled a trip to Mayweather's Michigan hometown for one of the fighter's early title defenses: "Floyd picked me up at the hotel and took me on a tour of his old neighborhood in Grand Rapids. He showed me where he used to live, where his grandmother lived, and even took me to the barbershop with him. He wanted me to know where he came from."

To a large degree, Mayweather's overpowering need to be the best ever is rooted in a disruptive childhood in Grand Rapids and the clear understanding, from an early age, that he was "born" to fulfill the destiny of the fighting Mayweather family.

He was expected to surpass his father, Big Floyd, and his uncles, Jeff and Roger Mayweather, the latter of whom held titles in both the junior lightweight and junior welterweight divisions. But despite his extraordinary success and all he has accomplished, Little Floyd never seems fulfilled.

It would be ironic if Guerrero, one of Mayweather's lesser-known adversaries, turns out to be the one who finally gives him the sort of epic struggle that virtually every great fighter must endure and triumph over. Even if Mayweather loses, it probably wouldn't be as horrifying as he imagines, and it just might provide a heretofore-unavailable opportunity: After all, it's the picking up of oneself after defeat and battling back that is the stuff of legend.

In the meantime, Mayweather could do worse than ponder the words of troubadour Leonard Cohen: "Forget your perfect offering. There is a crack in everything. That's how the light gets in."