Gregan came home in 47.63 seconds, with Tamac marginally ahead of him and Clemens Zeller from Austria (47.37) and Germany's Thomas Schneider (47.10) claiming the two automatic spots.

Speaking afterwards, a clearly frustrated Gregan, who has a personal best of 46.26, said: "I just don’t know what happened. I could hardly breathe out there. I'm absolutely shattered.

"I had to break my stride at 200 metres and after that I was fighting to make up ground, but I just lost my stride and then I seemed to lose the head and there was none of that smoothness that has been a feature of my running in recent weeks.

"That is a time I could run in my sleep. I can't explain it except perhaps the sinus problems I've experienced since I came here might have something to do with it.

"But right now I'm down in the dumps and in shock at being eliminated like that.

"I just ran like an amateur. My legs felt heavy and it's harder to take considering I ran a second faster in the Irish Championships in the Odyssey two weeks ago.

"Competing in a race like this so early in the morning is not good, but it's the same for everyone and that is not an excuse," added the Clonliffe Harriers clubman.

Cork sprinter Marian Heffernan also suffered a first round exit in the Bercy Indoor Arena, finishing fifth in her heat (54.94 seconds).

Heffernan, who was almost a second fastest when winning the Irish Indoor title a fortnight ago, had a solid first 200m but could not make up ground on the lead group.

She also missed out on a fastest loser's spot, being pipped by Patricia Lopes of Portugal, with just three-thousandths of a second separating them.

"I had a very poor first 50 metres and then was left having to fight to make up the deficit and it was just too much in the end," admitted Heffernan, who is the wife of international walking star Robert Heffernan.

Elsewhere on the opening day, Dan Mulhare missed out in a highly competitive 3000m heat that contained British ace Andy Baddley.

The North Laois clubman, who came sixth in 8:04.57, explained afterwards: "I have no excuses for not making the final. I just need to get my 1500m time down by several seconds if I hope to keep up with these guys.

"They have 1500m times that are several seconds faster than me and that pace is just a breeze for them.

"I did my bit to try and get a strong pace going but when it came to the last couple of laps that vital speed was not in my legs. But I intend to work harder and harder and it was just fantastic to get this type of experience out here."

There was better news for Letterkenny's Darren McBrearty who qualified for tomorrow afternoon's 800m semi-final as one of the fastest losers.

The 19-year-old finished fourth in his heat, clocking 1:49.74 which actually has him as the fourth fastest qualifier from today's four heats.