LAS VEGAS -- It's that time of year in Las Vegas. The cabbies sit up a bit straighter and drive with a purpose. The working girls that litter the hotel bars are a little prettier than usual, dressed in their Sunday (early morning best). And amidst the trillion liters of cool, canned oxygen that flow through the crowded, cavernous gaming rooms, there is a palpable buzz, just like the one that ran through your house when your parents told you Santa Claus was coming to town.

	Hard to believe De La Hoya will retire if he loses this rematch.

It is, of course, the much-anticipated rematch between Sugar Shane Mosley and Oscar De La Hoya, a fight that the cognoscenti have been buzzing over for months. All week they've been coming to sin city; at first slow and steady, then faster and faster, like raindrops filling a windshield. They are excited and eager because this isn't a Big Fight. A Big Fight is marketed by the standard industry shysters, and features two marquee fighters, one of whom is generally past their prime and fighting not for glory but for lawyers' fees and alimony payments. It garners impressive pay-per-view numbers, attracts the typical ringside Hollywood hipsters, and is rarely worth the time spent watching.

This fight is different. The 16,000-plus sell-out crowd, some of whom will lay out eight to 10 times the face value for a seat, are getting themselves a Superfight. The Superfight has some of the same elements of a Big Fight, like staggering paychecks, the pay-per-view numbers, the famous ringside faces, but there is something also starkly different.

First of all, the fighters are exceptionally matched, evidence of which can be found in the tape of their first, sensational June 17, 2000 bout, capped by an inspired 12th round that gave Mosley a slim split decision. Both fighters are a bit older now (De La Hoya 30, Mosley, 31), but neither is punchy nor paunchy. De La Hoya's back-alley beating of Fernando Vargas proves he's still got the power to punish, and Mosley's still retained much of the speed that once made him the top pound-for-pound fighter on the planet.

Yet there is more to the Superfight that separates it from all others. Like dark thunderclouds in the late summer sky, there is the inevitable feeling that a change is afoot, and that the loser's place in the sport will never be the same. A Superfight has significance that Big Fights lack - Ali/Foreman, Leonard/Duran II, Jones/Toney compared to spectacles like Tyson/Lewis. There is simply much more at stake.

For De La Hoya (36-2, 29), he has stated simply that he'll retire if he loses. With a music career, a burgeoning boxing promotional company, and all of his senses and a handsome face in tact, it sounds ideal. But for a man who's spent a life as a perfectionist, accumulating the medals, the titles and the countless millions, he will not live easily with losses to Mosley looming over him. The regret, the lack will eat at him, and it's the sort of thing that unfortunately brings fighters back to the ring later in their career for Big Fights.

Mosley (38-2-0-1, 35), on the other hand, is faced with the ultimatum -- win or die. Not die literally, of course, but professionally. Since snatching the title from De La Hoya, Mosley is 3-2 yet hasn't won a fight in his last three attempts (two losses to Vernon Forrest and a no-decision to Raul Marquez). The man of immense skill and heart now dangles precariously over the cliff -- a win will propel him back into the spotlight and reinstate his status as one of the sport's best, while a loss will certainly relegate him to the second tier of the division. The talk will be of squandered potential, fading talent, and to a fighter, than obscurity is nothing short of death.

Tim Struby is a regular contributor to ESPN Magazine. He has written articles on the Klitschko brothers and Roy Jones.