Tonight at the MGM Grand, before a crowd that appeared not quite at capacity, Floyd "Money" Mayweather (41-0) offered Shane Mosley (46-6) a lesson in the art of choreography. By the end, he also added lessons in trash-talk, counterpunches, pot-shots, and how to make a man look his age.

While Mike Tyson was present, he was overshadowed by Muhammad Ali, who entered the arena just past 7:00 p.m. Before two profoundly important fighters to the modern era in Mosley and Mayweather, Ali's presence could not but impose on the action the image of his legacy.

Drew Bundini Brown, the court jester in residence of Muhammad Ali's entourage, is said to have coined, "Float like a butterfly. Sting like a bee." The enduring myth of Ali is in part a product of his ability to mime both invertebrates with one fluid punch - to do what he said he would. Tonight, in the opening rounds, Floyd Mayweather and Shane Mosley divvied up the tasks of greatness, as Mayweather played butterfly to Mosley's bee. Each champion has at times accomplished half the greatness over a lifetime that Ali once did in eight words, but rarely both in one night. Mayweather did not get there tonight, but came close.

Three days prior to the fight, Mosley's trainer Naazim Richardson spoke of the ease with which a fight appears from the vantage point of the spectator: "At home on the couch, I'm 475-0." Despite his sagacious dispensation to steward his charge through the bout, Mosley was repeatedly frustrated. The gameplan deteriorated as Mosley appeared to lose steam once his body blows wouldn't land, and his knockout blows fell out of orbit after the second round.

In the first, Mosley came out game, equally aggressive as ineffective. . By the second, he had found his range. Within moments of a Mosley sloppy, looping right hand as if thrown as an elaborate ruse, Mosley then stunned Mayweather with a one-two combination. Mayweather's science is as quiet as his trash talk loud, and by the third he observed from the ring what was surely apparent from the couch: Mosley's feet would not oblige his hands to follow up combinations once Mayweather pivoted off a counter jab. Rebounding spiritedly, Mayweather showed he had a fortitude his harsher critics had questioned over the years.

As the fight reached its 6th stanza, a margin on the scorecards began to widen as did Mosley's aging hands. A Mayweather clean right hand counter landed that round. Due to the spartan action to that point, the crowd responded as if it had felled Mosley, Mayweather, and the referee all in one blow. The damage, however, was done: Mayweather had homed in on Mosley and could foresee his right.

For an ailing boxer, heart may be cynically defined as a euphemism for a failure to adjust to punishment combined a willingness to endure it. Through the sixth and into the seventh, Mayweather landed counter right hands that seemed each by each to compound in power. Mosley began to show heart.

Mayweather meanwhile had begun to taunt and grin during clinches in which Mosley continued to hit, as if empowered by the blows.

In the eleventh, Mosley attempted to rediscover his legs. As he bounced up and down like a teenager at a YMCA, Mayweather hit him easily, but lightly, as if to remind him at how stupid bouncing like that looked. Mayweather refused to risk taking a chance at a knockout as the paycheck came closer to his grasp. No knockout or knockdown occurred, and the fight, perhaps with Mosley's career, finished summarily.

Mayweather won on all three scorecards by unanimous decision. As Tyson left early in the 12th, having seen all he needed, many eyes from the audience were drawn to the man once heralded as the greatest heavyweight since Muhammad Ali.

Should a fight against Pacquiao now not occur, the legacies of its three participants will correspondingly suffer: Mayweather's, Pacquiao's, and the sport of boxing's in our era.