Oscar De La Hoya went to the gym every day high in the San Bernardino mountains in the summer of 1999, but his thoughts drifted more than 3,000 miles away, to a sweltering sweat shop that doubled as the training facility for Felix Trinidad.
De La Hoya was preparing to meet Trinidad on Sept. 18 of that year in a bout between unbeaten welterweight champions that was so big it was dubbed "The Fight of the Millennium."
And even though De La Hoya knew – knew – he had the physical tools to win the fight, he would fret about it constantly.
"It's constantly in your mind that this guy has never tasted defeat and you just can't help but ask yourself, 'Am I doing everything I can to be the first one?' " said De La Hoya, who lost a highly controversial decision in that bout in what at the time became the largest non-heavyweight pay-per-view in boxing history.
And, said De La Hoya, those kinds of thoughts are dominating the minds of super middleweight champions Joe Calzaghe and Mikkel Kessler as they make final preparations for their title unification bout on Saturday before a nationally televised audience in the U.S. on HBO and in front of an expected partisan pro-Calzaghe crowd of more than 50,000 in Cardiff, Wales.
Calzaghe, who is 35, holds the WBO super middleweight belt. He's 43-0 with 32 knockouts as a pro and has held a world title for more than 10 years continuously. He hasn't lost since he dropped an amateur bout in 1990.
Kessler, 28, is 39-0 with 29 knockouts. He holds the WBA and WBC belts and jokes he hasn't "thought of losing, let alone come close to losing."
But while most fights come down to hand speed and punching power and strategy and technique, De La Hoya and Hall of Famer Sugar Ray Leonard agree that the Calzaghe-Kessler fight will be decided by whoever turns out to have the mental edge.
Leonard, who defeated Thomas Hearns in an epic 1981 battle of welterweight champions, said the mental side of the game is too often overlooked.
"One of my advantages in my career is that I was strong mentally," Leonard said. "When I fought Tommy, even though I knew how good he was and even though everyone kept pointing out to me how strong and dominant he was and how many excellent fighters he had just run over, I never for a moment doubted I would win that fight.
"I just believed I would find a way to win. And when you have that belief in yourself, it eases a lot of pressure and things go a lot better for you. When you have doubts, it puts pressure on you and you don't perform as well."
Predictably, neither Calzaghe nor Kessler will admit to any doubts. But Calzaghe, who already won one such fight when he routed Jeff Lacy in a WBO-IBF unification match in 2006, said the confidence comes from preparation.
He said he had prepared so well for Lacy and had an answer for every contingency that it afforded him great peace of mind. He knew there was little chance of losing.
"Not too many Americans really thought I had a chance against Lacy and, if the truth be told, I don't think there were a lot of people over here who did, either," Calzaghe said. "I knew I'd put the time in. I was completely healthy, which I haven't often been, so I didn't have that hanging over me.
"And there was nothing that could happen in there that would be a surprise. I was in the best shape I was in for a fight, I was mentally prepared for anything he could bring and I felt completely relaxed because of that."
Part of going into training camp is to prepare mentally, as well as physically, Kessler said.
He said he knows when he looks into an opponent's eye at a prefight event – or even as the referee is giving the final instructions – he is going to win and that his opponent is broken.
He has heard a lot of talk, and knows he'll be a decided underdog in front of a hostile crowd at Millennium Stadium, but has been through it all before.
"If you have the experience, it makes a big edge mentally because you know you can do it and then you just react, instead of thinking," Kessler said. "It's one of those things where you just build yourself up to know you can't lose and so you can go out and let it all go without any caution because you're so sure you've done what you've needed to do." De La Hoya, who is picking Kessler, predicted the high stakes mental chess game will continue until the bell sounds.
A fighter has an inner radar to detect whenever an opponent has self doubts.
"As fighters, we have this sixth sense and if you are afraid, we know it and we go for it," De La Hoya said. "And this last couple of days, each of these guys is going to be looking at each other and seeing if he can find some kind of a weakness he can take advantage of."