LAS VEGAS - Floyd Mayweather Jr. has been doing this all his life, since he was a scrawny kid seeking solace in the gym. The ring is his comfort zone, and he'll enter it Saturday for the 43d time as a pro, certain as ever that when the night is through he'll not only be a lot richer but still unbeaten.

Miguel Cotto is equally certain that he can be the first one to conquer Mayweather.

"I don't need anyone else giving me a chance," Cotto said. "If I can trust in myself, I don't need anyone else believing in me."

Not many are, especially the oddsmakers who make Mayweather a 6-1 favorite in Saturday night's fight. But if any fighter is a live underdog it's Cotto, a relentless puncher who believes in himself again after finally avenging a beating he took from Antonio Margarito four years ago.

Cotto stopped Margarito in their rematch in December, and will be defending his version of the 154-pound light middleweight title against a fighter who knows how to promote a big bout almost as well as he knows how to fight one.

Mayweather has won all 42 of his fights as a pro while becoming the biggest pay-per-view attraction in the sport. If he needs any added incentive to win this fight, it would be that it might make the nights pass easier when he goes to jail June 1 for what is expected to be a two-month sentence for domestic abuse.

There are still questions, though, about why Mayweather doesn't fight Manny Pacquiao in the fight most boxing fans want, a fight that would be the richest in boxing history. Mayweather continues to insist he doesn't need Pacquiao, and he may be right. He gets the biggest cut of the revenues for all his fights, and he probably makes at least $30 million for this one. He may not be doing boxing any favors by not giving the sport a desperately needed fight, but he's doing fine for himself.

Despite the odds in his favor, there's a decent chance Mayweather could be challenged by Cotto, who will be fighting at 154 pounds for the fourth time and appears to be comfortable at the weight. Mayweather agreed to move up from 147 pounds to take him on in a scheduled 12-round fight that will be televised on pay-per-view.

Most in boxing, though, believe Cotto (37-2, 30 knockouts) is too slow for the slick Mayweather and will be unable to apply enough pressure to land effectively and often. They believe if he cannot get inside he will be easy pickings for Mayweather, who in recent fights has shown an inclination to fight more flat-footed rather than try to win by playing defense.