For everyone else, there was absolute shock – the men’s 1500m again proving itself as the most intriguing, engrossing and utterly unpredictable event in athletics.

At the Japan National Stadium in Tokyo on Wednesday, Portugal’s Isaac Nader produced the biggest upset of the World Championships, kicking to victory in 3:34.10 ahead of Britain’s Jake Wightman (3:34.12), with bronze going to Kenya’s Reynold Cheruiyot (3:34.25).

Coscoran, following a race where he struggled to land a blow against the world’s best, hit the line in 3:35.87, knowing it could have been much more, hoping and believing that one day it would be.

“I’m a little disappointed,” he said. “I wanted to finish higher up. It’s my first world final so there’s a lot of positives. It’s tough to get it right on your first go but next time around, I can give it a good crack. Sometimes it just doesn’t go your way. Next time I hope it will.”

At the Paris Olympics last year, the men’s 1500m was the race of the Games and it will take something seismic over the next four days to produce something with as many theatrical twists as this – a race that made every guru seem clueless, which turned the form book on its head.

It was bizarre, yet utterly brilliant.

With the elimination of former Olympic champion Jakob Ingebrigtsen in the heats, the field had no clear pace-setter and into that void stepped race favourite Niels Laros of the Netherlands, the 20-year-old towing them through 400m in a steady 59 seconds. That was the first surprise, given most expected Laros to sit and wait given his vicious finishing speed.

With just over two laps to run, former world champion Timothy Cheruiyot of Kenya – who trains with Laros – took over in what looked a deployment of team tactics.

Coscoran was 11th at 800m and, soon after, reigning world champion Josh Kerr appeared to pull a muscle and dropped to the back like a pebble through water. He tried to soldier on, but it was a losing battle and he trailed home last.

Coscoran, meanwhile, was trying to move up, but that was no easy task in company like this. “I was hoping to be in a higher position with 400 to go but there were 14 guys in that race instead of 12 so it makes it a bit more carnage,” he said. “It was hard to get into those positions.”

Cheruiyot and Laros had command up front with 300m to run, but then along came Wightman, as classy as he is tactically astute, and he utilised his vast range of gears to sweep to the front entering the final turn.

Laros had him right where he wanted, but the young Dutch star just didn’t have the legs to go by and he faded to fifth – something few would have predicted.

Instead, moving from fifth to first over the final 100m – which he covered in a blazing 12.28 seconds – was Nader, a 26-year-old who had only finished 12th in the last world final. Hands up those who called him as the champion.

Laros was utterly deflated with his run, though it seems inevitable his day will come. “The preparations were great, I cannot think of anything that could have gone better,” he said. “So it’s a bit shit.”

Coscoran, who was the first Irishman to make a world 1500m final since Ciarán Ó Lionáird in 2011, knew his positioning had cost him. “I made too many surges in the last 400 because I’d too many bodies to go around,” he said.

“Then with 100 to go those surges caught up with me and I started to tighten and go backwards. I went in with a good game plan, it just didn’t go my way. It’s a learning experience.” He will be back in action in the 5000m heats on Friday.

Meanwhile on Thursday, the Irish focus switches to the 800m where Mark English and Cian McPhillips both hold live chances of reaching the final.

The three semi-finals get under way at 1.45pm Irish time, with just the top two from each race advancing, along with two time qualifiers across the heats.

English is the third fastest this year in his semi-final behind the Paris Olympic silver medallist Marco Arop and bronze medallist Djamel Sedjati, while McPhillips has to contend with four men who have run 1:42.

However, the 23-year-old Longford athlete was hugely impressive in winning his heat and will be dangerous if he’s still in contention as they turn for home.

Irish in action, Thursday (Irish time)

1.45pm: Mark English, men’s 800m semi-finals

1:53pm: Cian McPhillips, men’s 800m semi-finals

World Athletics Championships, Tokyo – Live, RTÉ Two, 10.45am; BBC Two, 10.30am