Mageean had to be patient for one more race to finish before having it confirmed that she would take to the line for tomorrow’s decider in the Serbian capital.

The Irish star had trotted around the first five laps in second place behind Turkey’s Meryem Akdag, but things changed dramatically in the final 300 metres, with Swede Meraf Bahta coming onto the scene, overtaking both Akdag and Mageean on the outside.

Akdag would fall backwards dramatically to finish sixth, while Mageean needed to show her trademark great resolve to claim fourth behind Bahta, Britain’s Sarah McDonald and Belarussian Daryia Barysevich in a blanket finish.

Mageean’s time of 4:12.81 may have squeezed her in as the last of the fastest losers, but by a comfortable margin - a full second and a half over Simona Vrzalova of the Czech Republic, who was next fastest.

The Portaferry athlete admitted: “That’s not how I wanted to leave it!

“I definitely wanted to secure it that bit more convincingly, but I made it through to the final, and that was my aim so I’ll go back and see how I feel and get ready for tomorrow.

“I was sitting there watching that third heat with my fingers crossed. I don’t like leaving it like that, and I don’t want to be in that position again.

“The plan was to make the final and I’m still there. Now that the final’s decided, it’s anybody’s game once you’re in it so that gives me confidence.”

Kerry O’Flaherty was eliminated after finishing sixth in her 1500m semi-final, in 4:23.82, reporting some illness afterwards - Poland’s Sofia Ennaoui won this semi-final in 4:11.91.

Brian Gregan gave Ireland the other high-point of the opening day by finishing second in his first-round heat of the men’s 400m behind double world and European champion Pavel Maslak of the Czech Republic, but fell asunder in the evening semi-final to cross the line in sixth place.

Gregan’s heat time of 47.62 - just 0.05 behind the great Maslak - was not matched in the semi by the Clonliffe Harrier, with 48.08 seeing him eliminated.

Maslak, as it happened, expanded his abilities by speeding up to 46.45, and he looks favourite again to take gold in Belgrade.

Gregan responded afterwards: “I felt good after my first race, and then while warming up (for the semi-final), I just felt flat.

“Once the gun went and I took a couple of strides, I knew I was in trouble.

“I knew it was going to be a long 400 metres!

“There was just nothing there. Four weeks ago, I was a little bit sick, but I got right for the nationals, but two weeks later we have these Championships, and I still wasn’t training properly, and the freshness wasn’t there.”

Eliminated after one race were Phil Healy and Sinead Denny in the 400m (both 4th in 54.80 and 54.20 respectively), Zak Curran in the 800 (4th in 1:50.87), John Travers in the 1500, Tomás Cotter in the 3000 (9th in 8:15.85) and Ben Reynolds in the men’s 60m hurdles semi-finals (6th in 7.81 seconds).

Travers was waiting for the decision an appeal after his semi-final exit in the men’s 1500 metres, after what sounded like a recall gun went off seconds after the start of his race.

The Donore Harrier slowed down after the second gun, as did one or two others, only for the race to continue.

It left Travers having to try and speed up to catch the leading five, which he was unable to do.

His time of 3:59.72 was the slowest of the entire semi-final round, and over 13 seconds outside his season’s best.

Travers reported: “We were about 40 metres in when a big loud bang went off from a second gun, so it seemed they definitely were calling us back for something, but the five lads ahead of us seemed to have a mission to keep going so myself and the Spaniard got sixty metres behind them and came to a jog and a stop.

“It’s strange, it’s the first time anything like this has happened to me.

“You can prepare for everything but you can’t prepare for that!”

Cindy Roleder added European indoor gold to her outdoor triumph from Amsterdam as the German won the women’s 60m hurdles in 7.88 seconds ahead of defending champion Alina Talay of Belarus and compatriot Pamela Dutkiewicz.

Behind them was world record holder Susanna Kallur of Sweden – a regular opponent in the noughties of Ireland’s Derval O’Rourke – finishing eighth in her last ever race before retirement at the age of 36.

Britain’s Andy Pozzi grabbed the men’s equivalent in a sprint finish by 0.01 seconds ahead of Frenchman Pascal Martinot-Lagarde.

Olympic Heptathlon champion Nafi Thiam of Belgium turned on the magic indoor to win the five-event pentathlon, Piotr Lisek of Poland appropriately won the pole vault, and Hungary’s Anita Marton won the shot putt, successfully defending the title first won two years ago in Prague.