Instead, he used his traditionally strong finish to make sure there would be no worries at all, winning in 49.79 seconds, having half a second to spare over Germany’s Felix Franz.

Barr knows he will have to quicken up in the semis, after Russia’s Denis Kudryatsev won his heat in a storming 49.05.

“I hadn’t really thought about the 7am start until today, that was a little bit of a shock to the system but I came out to run it, hopefully win it and get a decent lane draw for tomorrow,” the Ferrybank AC hurdler said of his 11am burst into action.

“I’m confident and happy with my run today.

“The only place I could ease off was in the last 80 metres. I’ll put in my trademark finish if I have to in the semi-finals!”

Jason Harvey bowed out of the same event by finishing seventh in his heat in 51.91.

Both Irish competitors progressed in the men’s 400m, with Brian Gregan going through automatically and Richard Morrissey hanging on as a fastest loser.

Dubliner Gregan finished third in a tough heat in 46.33 seconds, with Morrissey progressing as a fastest loser by finishing sixth in a personal best 46.20 seconds.

Gregan, who finished sixth in the 400m in Helsinki at the last European Championships two years ago when a groin injury struck him on the closing straight, admitted: “I had to get top four in that. I was ranked fifth going into the race, I had a really hard draw and finished third.

“That’s all I could ask for – to get top three. The other two guys were a metre or two ahead of me. I could have put the foot down and pushed it had I really wanted to but there was no point trying to kill myself. I shut down and got the automatic qualification.”

“It was hard work actually,” Morrissey said of his performance, adding: “I felt good for 300m and then tied up a little bit at the end, but it’s always good to get a PB, especially in a class race like that.

“I’m in the semi-final now and will have to see what I have left after I recover.”

Amy Foster had to wait before making it into the semi-finals of the women’s 100m, going through as a fastest loser.

The City of Lisburn sprinter was looking good for an automatic place in the next round until she was pipped on the line for fourth by bronze-medallist at the last Europeans, Lina Grincikaite of Lithuania.

The former European Under-23 champion clocked the same time as Foster, 11.51, but was given fourth with Foster fifth – the Irish athlete narrowly made it through as the fourth and last fastest loser, meaning Phil Healy of Bandon missed out by two-hundredths, finishing sixth in her heat in 11.53.

Foster, despite making it to the semis, was still annoyed by her final placing: “I’m not happy I didn’t get through on automatic qualification. I thought I could get top four. It’s unfortunate that both of us (Foster and Grincikaite) were given the same time and that it went in her favour.

“I had a good start, it was flat in the middle and I was coming again at the end.”

Healy, in her first senior Championships, was happy at how well she had done, but disappointed at narrowly missing out on the semis: “It was very close, only two metres out, two-hundredths of a second away from the last fastest-losers spot so it is gutting to come so close.

“To get to 11.51 was just the tiniest bit of a dip so I am gutted but to come to a senior major Championships at 19, I can’t really complain.”

Limerick hurdler Sarah Lavin was denied in the women’s 100m hurdles through, as she came through in eighth in 13.35 seconds.

“I couldn’t fault my first five hurdles,” Lavin said afterwards. “I went as aggressive as possible but I couldn’t control it I suppose and I hit two hurdles and they were gone from me then. You can’t do that in a senior championships.”

Later tonight, Mark English and Declan Murray compete in the men’s 800m heats, while Fionnuala Britton kicks off her marathon week with a medal chance in the women’s 10000m final.