On the wrong side of 40 and having been on the fringe of the Australian squad for more than two decades, Scott Westcott thought his Olympic dream was over.

Tomorrow he makes his Olympic debut in the marathon.

It is a goal he hatched as a 16 year old but has taken 25 years to materialise.

He has been incredibly unlucky in the past.

He ran qualifying times in the 5000m and 10,000m for the Sydney 2000 Games but missed out on selection.

He did the same for the marathon ahead of Athens in 2004 and Beijing in 2008. Again, he missed the selectors cut.

This time, again, there were no guarantees.

He ran a qualifying time at the 2015 Berlin Marathon to secure his spot, but the announcement was delayed a fortnight as another competitor unsuccessfully appealed his non-selection to an independent tribunal.

“Maybe it’s not the perfect system but it’s supposed to even out any unfair calls,” Westcott said on reflection.

“It was frustrating to have to sit around but it’s certainly nothing personal. I was confident that I had done enough.”

Now, just a month shy of his 41st birthday, Westcott will become the oldest Australian track and field athlete to make his Olympic debut.