What happened next still makes McGrory choke with emotion, 20 years later.

The grieving dad sat on his own in the middle of the Dunc Gray Velodrome, shut out the full-house crowd, and gave himself the mother of all self-talks.

The transformation was remarkable.

By the time the two Australian cyclists rolled up to the start line, McGrory could survey their rivals and silently sneer "you suckers".

Aitken and McGrory duly won Australia's most emotion-charged gold medal at the Sydney Games, a triumph that the two fathers forged from profound heartache.

Less than three months before, McGrory and his wife Donna had lost their first-born son Alexander at 11 weeks because of a heart condition.

Aitken and wife Natalie were rocked earlier that year when baby daughter Ashli was diagnosed with Rett syndrome, a rare neurological disorder.

Ashli died in 2009, aged 10.

On the morning of the race, McGrory woke up, looked over at his roommate Aitken, and apologised out loud.

Aitken was still asleep and only found out about it years later.

After seeing Donna and other family and friends at the track, McGrory knew he was at his crossroads.

"For the first time since we lost Alexander, I actually felt ... everything from this moment on is going to be up to me," he said.

"I just gave myself a really strong, stern talking to - just wise up, smarten up.

"Here's a challenge for you - can you still win this race if you're not at your best? Wow - wouldn't that be something special.

"It just went 'flick', like a light switch. Right, here it is, new challenge."

Aitken had also struggled mightily with his daughter's diagnosis, but eventually went to Europe for training.

When Aitken arrived in Germany he found a label maker and printed out "unbreakable", which was stuck in a prominent spot on his bike.

Aitken has his own moment of catharsis when he arrived at the track for their event.

"Something came over me, I thought 'I have to see my daughter'," he said.

"It gave me another boost - 'I have to leave every little bit out there'."

They rode a near-perfect madison, securing an unbeatable lead before the final sprint against formidable opposition.

"It sounds corny, but I looked up at all the other riders on the track (before the start) and I thought to myself 'you guys are suckers'," McGrory said.

"How dare you think you can beat us in this race on our track.

"Of course, we dominated.

"The power of the mind is extraordinary, both ways."

Australian Associated Press