Plod after laboured plod. "Whether it's for the gold medal, the world record or the 9,000-point barrier, it always comes down to the 1500," an exhausted O'Brien would say after staggering home in 4min 45.89sec to secure the gold.
Steve Ovett, in a famous dig at Daley Thompson, once described the decathlon as "Nine Mickey Mouse events followed by a slow 1500". Maybe Ovett should have tried it: launched himself at the pole vault, the high and long jumps, gone over high hurdles, sprinted, thrown and putted, all in two days.
If the title, world's greatest athlete, first bestowed on Jim Thorpe, decath-lon and pentath-lon gold medallist at the 1912 Stockholm Olympics, has little currency among the sport's elite today, nothing but admiration can be held out for the hard men of the decathlon.
The decathlon is a concentrated test of strength, stamina, speed and endurance. And late on Thursday night, it finally reduced Dan O'Brien to tears. It was the hurt as much as the realisation of victory that caused O'Brien to weep.
When O'Brien went off in the 1500m, he needed to stay within 32 seconds of Frank Busemann who had come out of nowhere to challenge for Germany.
Gulping in air as he approached the line, the effort of it evident in contorted features, O'Brien finished with plenty to spare.
In becoming the first American to win the title since Bruce Jenner in 1976, O'Brien had not only seen off Busemann and the bronze medallist, Tomas Dvorak. Here was O'Brien's redemption for his failure in the US Olympic trials four years ago that resulted in the collapse of a $25m (pounds 15.9m) advertising campaign.
Born to a Finnish mother and half-black father, O'Brien took the name of the multi-ethnic Oregon family who adopted him. Later, at the University of Idaho, away from the O'Brien family discipline, he fell from grace. Attainment in sport came third behind booze and pot. Tutors despaired of him. He wrecked a car and was picked up for drug possession. Broke, kicked out of school, friendless, he would not have made it to Atlanta but for the O'Briens' understanding and the faith his coaches had in him.
The 1992 US Olympic trials brought another relapse. Shattered by his failure to make the team for Barcelona, O'Brien got so drunk that he wound up in hospital, needing stitches for a gashed hand, so dehydrated that he was given intravenous fluids.
"I try to forget about the troubled past, the problems I went through to get here," he said, at last the Olympic champion. "Every day for four years, I've woken up telling myself that I wanted the gold medal. Now it's mine and I can tell you it's an awesome feeling. I guess this is as close as I'll ever get to being as famous as a rock star."
The decathlon is as much a trial of mind as body. On the final day, O'Brien's lead was cut to 71 points by the 21-year-old Busemann, who splashed through puddles on the track to record the best 110 metres hurdles time ever seen in a decathlon, 13.66sec.
Needing to spin the discus past Eduard Hamalainen, the Belarussian who has a reputation for strong finishes, O'Brien came up short again, but extended his lead to 124 points.
The subject of an NBC TV special, O'Brien was given no respite by their cameras. Everywhere he turned, there was a lens, recording every move, every gesture.
Now O'Brien, a handsome figure at 6ft 1in and 13st 2lb, came to the event that cost him a place in Barcelona. Amen Corner. The pole vault.
This time, O'Brien's coaches were less worried by three unsuccessful attempts than Hamelainen. The Belarussian had failed more often than O'Brien, but also managed to go higher, clearing 5.00m on a borrowed pole. "This guy's an animal," one of O'Brien's coaches said, "you can't count him out. But don't worry - just score your points."
As O'Brien prepared for the javelin, he was ahead by 142 points. Then Busemann came at him, sending the spear to a career-best 66.86m with his opening throw. O'Brien also threw farther than ever before, two inches further than the German, to keep his margin intact.
So to the final discipline. It was around 10.30pm when O'Brien went off in the final heat of the 1500, but there was plenty of support.
Few in the audience understood what was required, and as he dropped further and further back, they assumed he was beaten. "Come on Dan," they shouted. "Get up there."
O'Brien slogged on. Thirty-two seconds to play with. It was enough.
"It was tough," he said. "All the way through, those guys kept coming at me from all angles. It wasn't one of my best competitions.
"I'm tired, it hurts, I'm numb. If there had ever been a day when I didn't think I could do this, that would have been the day to quit."
On the track, O'Brien had fallen into the embrace of the man who adopted him. Jim O'Brien wore a shirt that said, "Dan's Dad, World's Greatest Athlete".Reuse content