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In the MGM Grand, full to the rafters for Saturday's megafight, Floyd Mayweather Jr., an American welterweight (40-0; 25 KOs) jauntily strided toward the middle of the ring. The boxer, who claims to be better than Sugar Ray Robinson and Muhammad Ali, wore red faux leather trunks trimmed in black fur, his 5'8" body rippled with muscles and a confident grin. His weight was announced at 146. In the opposite corner stood Sugar Shane Mosley (46-5; 39 KOs), another American, about the same size, give or take a pound at fight time, but five years his senior.

Mayweather is arguably the greatest defensive technician in the history of the sport, but many boxing fans, who pay to see two men pummel each other silly, don't always appreciate his gift for dodging punches—and worthy opponents. Enter Mosley, Mayweather's quickest and most formidable foe to date. "I believe I am faster," Mosley, a natural welterweight, told me before the fight. "I have never faced him so I don't know. But I am fast." Most of my colleagues in press row, Nevada bookmakers, and the betting public didn't think Mosley, 38, was fast and powerful enough anymore, and made the veteran a 4-to-1 underdog. And by the beginning of Round 3 Mosley was breathing through his mouth, a sure sign of fatigue.

After the opening bell, Mosley, clad in black shorts trimmed in baby blue, stepped forward to pursue the younger man. Mosley connected with some right hands in the early rounds but mostly he punched the air. In the second round Mosley nearly pulled off the upset. The crowd chanted, "Mosley! Mosley!" after he landed a big right, which seriously stunned Mayweather. "It's a contact sport," says Mayweather. "You're going to get hit, but when you get hit you suck it up and keep fighting." To regain his composure, he told me after the fight, he thought about his family, and it calmed him down. The blow was the lone highlight of the night for Mosley. His age (he complained of a tight neck) and Mayweather's right hand over Mosley's jab caught up with him as the fight wore on. "He was too quick, and I was too tight," Mosley admitted later.

Mayweather, who is usually speeding around the ring like a Nevada jackrabbit, decided to stay in the center of the ring and go toe-to-toe. It seemed to shock everyone, including his opponent. Mayweather cleverly jabbed and counter-punched Mosley, and though the fight went 12 rounds, it was dominated by Mayweather, who won in a unanimous decision.

Mayweather will now be considered the best boxer in the world. Manny Pacquiao of the Philippines will be ranked number two. Mosley is usually rated a close third. Tommy Hearns and Sugar Ray Leonard, two veterans of the last great era in boxing who fought each other 29 years ago, were on hand for the fight. Leonard described the modern era as a "dark time in boxing," but his presence at the match seemed to imply that Mayweather-Mosley might help the sport revive its glory days. It was hardly a classic—no blood stained the ring, and there wasn't enough back-and-forth drama—but Mayweather proved he has few equals, now or in earlier eras. It has been theorized that Mayweather's fights draw millions of pay-per-view buyers because people are desperate to see him lose. Mayweather must be laughing his way to the bank. He was guaranteed $22.5 million for the bout but could make more depending on pay-per-view buys; Mosley has a guarantee of $7 million.

Now the boxing world turns its eyes to Pacquiao. The two were supposed to fight in March, but negotiations broke down after Mayweather insisted on Olympic-style blood-testing. While Pacquiao has never tested positive for a performance-enhancing drug, the winner of seven titles in seven weight classes felt bullied by the request and refused to agree to it, saying drawing blood before a fight weakens him. Many in the boxing world perceived Mayweather's request as a way to avoid Pacquiao, who was recently named the fighter of the decade by the Boxing Writers Association of America. Now the (negotiating) table has turned. For his reputation and for the sport of boxing, the pressure is now on Pacquiao to agree to a fight.

If the men can see beyond their own needs and work out their differences, the dream matchup could happen as early as this fall. Pacquiao is currently running for Congress in the Philippines; the election is on May 10. I was in the Philippines several weeks ago, and Pacquiao was attracting thousands of people at his rallies, often held in coconut jungles, where he talks about his own abject poverty growing up in his impoverished and violent southern province. People line up a hundred-deep at Pacquiao's General Santos City house to beg for money. He pays their medical costs and even buys coffins because people can't afford to bury their dead. According to my sources, Pacquiao has spent $10 million on the campaign. To get back into financial shape, he needs to fight again. Fighting Mayweather could be the most lucrative boxing match ever, garnering $40 million per fighter.

After Saturday's fight, Mayweather—clad in a suit, tie, and fuchsia shirt with diamond-encrusted "MM" cufflinks—talked about his reputation (he was upset that so many Americans like Pacquiao) and his impending vacation (perhaps a Disney cruise with his family). The sporting world will now have to watch and wait as Mayweather and Pacquiao work out their differences.

"If Manny Pacquaio takes the blood and urine tests, we can fight," says Mayweather. "If Manny wants to fight, it's not that hard to find me."

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