So he shot to the lead in the 5000m final and for a while he thought his crazy-brave tactic might work.

Championships races are littered with runners who seek their early moments of fame to spend a lifetime saying they once led the big race, but Tiernan didn't just lead this race he re-shaped it.

It was going slowly so he picked up the pace. Within a lap he led by ten metres, then by 15 metres. Farah was forced to rethink his plan and ultimately it might have cost him the gold.

Tiernan led until there was just 600 metres to go, when finally the pack folded him in and he was pushed back to 11th place.

Ethiopa's Muktar Edris won gold in 13:32.79 from Farah, who took silver, and Paul Chelimo, bronze. Tiernan was eleventh in 13:40.01.

"I don't have any regrets from it, I could have hung back and waited but you know you have got to give it a good crack and I came here to try and win a gold medal, as unrealistic as that sounds that is what you come here to do so you give it your best shot and that's what I did today.

"You are thinking that (when are they coming for me?) but you are also thinking if I am going to do it this is my chance so you have to make the most of it ... you are thinking maybe I can do this, it's a great opportunity for me I am going to give it a good crack but you are always knowing in the back of your head guys like Mo and Muktar and even a guy like (Briton) Andy Butchart you know they are right there.

"It's intimidating but that's what you do it for you are out here and you want to push them and see what you can do."

It was not only a surprising race, it was also a brave approach given his disappointing run in the 10,000 only a week earlier, when he became so fatigued by the 7km mark he became delirious. He wandered across lanes at one point yet still managed to finish the race.

"I was buggered, I was a little delirious [and] it wasn't pretty. I honestly can't remember much of those last few laps, the only thing I can remember is coming through and looking at the clock and thinking 'oh man I still broke 28' and the guy's waving his finger at me like you have one more lap buddy," he said.

"You look back and you can laugh but you have to learn from it."