It was meant to be the day that Paula Radcliffe was crowned Olympic marathon champion, elevating her to the pantheon of British sporting immortals.
It was not supposed to end with her slumped on an Athens pavement, crying bitter tears of pain and frustration.
So what went wrong?
How did the current world record holder, a woman who had run more than two minutes faster than anyone else in the field, not only fail to take gold but also fail to even finish?
Radcliffe is a woman famed for her ferocious work ethic and absolute determination to do whatever it takes - no matter how painful - to make herself a better runner.
She knew it would be scorchingly hot in Athens, she knew there was a danger of dehydration, and she would have trained accordingly.
But what no amount of preparation could do, no matter how obsessive, was protect her body from the vicious conditions she experienced on Sunday.
It was 33C at the start of the race, so hot that even standing still was extremely uncomfortable.
Radcliffe has won races in adverse weather conditions before - notably her international breakthrough at the 1992 world cross country championships, when she triumphed despite sub-zero temperatures and a blizzard.
But this was something else entirely. Despite taking on electrolyte replacement drinks at every feeding station and wearing an ice vest for an hour pre-race, Radcliffe was first sapped and then slain by the relentless heat, both physically and mentally.
Sports psychologist Anthony Gleadall says: "Dehydration means the brain starts to slow down.
"The heat and humidity would have affected her concentration, thought processes and ability to think lucidly."
Last reserves of energy
Under intense pressure for the first 15 miles from the rivals on her shoulder, Radcliffe then had to try to respond when Mizuki Noguchi and Catherine Ndereba accelerated away from her
Forced to abandon her front-running plan, she was forced to expend her last reserves of energy on chasing them down.
Initially she seemed to be closing the gap - but that enormous effort sucked the final vestiges of strength from her body and left her with nothing more to give.
Perversely, Radcliffe's defeat does not mean that she is no longer the best marathon runner in the world.
She is. But because each marathon course is different, comparisons between some races just do not work.
Had this race been run in springtime, or even in the cool early morning, Radcliffe would have run away from Noguchi and Ndereba just as she has in the past.
Her defeat in Athens was a very specific one - a direct result of the timing of the race and the conditions on the course.
So what now for Radcliffe?
Olympic gold was going to be the pinnacle of her career. Now that medal has slipped away again, have we witnessed the best she has to offer?
Beijing in 2008 seems an awful long way away, after all. And she already holds the marathon world record. What else is there for her to do?
Radcliffe left the course in tears
Win a global track title, for starters. To think of Radcliffe as someone who might be crushed by adversity is to completely misunderstand her character.
Radcliffe has always had to fight against the odds to succeed. In her first national race, at the under-12 English cross country championships, she finished 299th.
Remember what happened after the last career crisis?
At the 2001 Worlds in Edmonton, having already missed out on Olympic and world 10,000m gold, she finished outside the medals again despite a complete tactical re-think, and then had a very public slanging match with husband Gary Lough.
On that August night in Alberta, anyone suggesting that Radcliffe would be hailed as the greatest female distance runner in history within three years would have been laughed out of town.
But Radcliffe kept the faith, kept training, and kept improving.
Within 12 months she had her first track titles, taking Commonwealth 5,000m gold in Manchester and then destroying the European record in taking 10,000m gold at the European Championships in Munich.
Then came the record-breaking triumphs at the London and Chicago marathons.
Radcliffe will also be just 34 years old in Beijing - old for a sprinter, but the perfect age for an endurance athlete.
She loves running. She loves competing.
"If I worked in an office, I would still be trying to get out for a run," she says. "It's addictive. I love it."
All of which points towards her continuing her quest for Olympic gold.
There may well be a break so she and Lough can start a family. But childbirth is likely to have only beneficial effects on her physiology.
Sunday evening was a soul-destroying time for Radcliffe. But it was not the end.