These are always the hardest hours and, for Oscar de la Hoya and Felix Trinidad, today will drag like no other. They have both been here before, in that bleak and terrible place where fighters wait for night to fall and the first bell to ring. Trinidad has heard that opening sound 35 times, while De la Hoya has felt the same sweet release before each of his 31 fights.

At 26-years-of-age, and as unbeaten and celebrated welterweight champions, they should be journeying into familiar territory. But tonight will be different. While the rest of us in Las Vegas are lost in the brutal thrill of an uncertain contest, or in our more grandiose claims that De la Hoya and Trinidad are fighting for the salvation of boxing, they face new and more personal traumas.

"It's the darkest and most introspective time for a boxer," Sugar Ray Leonard said earlier this week. "And when it comes before a fight as big as this, a fight which only rolls along every 10 years, you have to look inside yourself like never before.

"For both these guys, defeat would be horrendous. You can not even begin to imagine what it would be like. It'll cost them millions of dollars, but that won't matter. Their pride will never be the same again. And that hurts the most. To lose for the first time is a savage and lonely thing."

Like many other boxing insiders, Leonard insisted that he cannot pick a winner. "The only thing I know is that one of them will get stopped. But who needs to win the most? In the end, it will come down to mental and even spiritual desire."

Leonard is almost certainly right, although counter-arguments have been made that the outcome will be decided by Trinidad's greater skill or De la Hoya's deeper experience of the booming hype which surrounds a huge fight in Las Vegas - otherwise known, in American boxing, as "Oscar's town". But it is just as easy to say that De la Hoya has the quicker hands and the superior defence, while Trinidad has the sharper hunger for victory.

Both fighters are dangerous, if also vulnerable. Trinidad has won a remarkable 90 per cent of his fights before the end of the fifth, but has been knocked down six times himself - and always in the second round. De la Hoya has taken a count three times, most seriously this February when he was decked by Ike Quartey. But he also floored Quartey twice to clinch a narrow points victory. While Trinidad has often looked sensational, he is yet to be tested by a fighter as exacting as Quartey.

De la Hoya has since sent out a mix of messages in an attempt to imply that he is as likely to stand his ground and seek a quick conclusion rather than take his more probable route - which, wisely, requires him to move laterally in an effort to evade Trinidad's power. He has also switched between suggestions that he will rely exclusively on his lethal left hand or, unusually, introduce his right as a way of surprising Trinidad.

There is less ambiguity in the Puerto Rican. "When I hit a boxer," he stresses softly, "he falls. I'm in the best condition of my life and I can't see how De la Hoya can stay on his feet. I'm going to knock him out before the sixth round."

Tonight, after such a long day, anything is possible, but regardless of who wins, the lives of these two great fights will change forever.