Pyrotechnic smoke bellowed about the means streets of Zenica; boisterous, haunting and vociferous chanting filled the poorly lit lanes – all roads leading to the Bilino Polje Stadium.

The slow slog out of Sarajevo had already added to the anxiety, as Ireland set off on the first leg of the play-off that would eventually end up in France the following summer.

The old ground would mind of those great Dalymount days of the 1980s when Ireland played their home games in Phibsboro’s finest, before Lansdowne was illuminated.

However it was Ireland, in a hostile Bosnian environment, who flourished in their Euro 2016 play-off, while Denmark left neighbouring Sweden with hope and little else. 

Martin O'Neill's men are unlikely to face as febrile an atmosphere in the Parken Stadium tomorrow, but the Republic of Ireland manager will surely take strength from that experience of two years ago.

Police escorts were needed to take the frenzied factions of home fans through the exploding fireworks and sulphur-smelling haze. There was certainly an edge.

Still two hours ahead of the game, the vocal youth had been safely secured inside the stadium and their repetitive, intimidating arrangements charged the atmosphere to the limit.

By kick-off, the place was set to erupt. The hardy mob of Irish souls, sardined into the caged-off away area were adding to the occasion, attempting to bounce the strains of the Fields of Athenry around the old arena.

Ireland faced a footballing side with a host of top-class talent, including former Manchester City striker Edin Dzeko, and Serie A stars Miralem Pjanic and Senad Lulic.

The home side took control of the game early on and put real pressure on the Irish rearguard. But Ireland embraced the hostile environment - perhaps aided by the League of Ireland aspect to the surroundings - and got numbers behind the ball, preventing the home side from really threatening in the final third.

The storm was weathered to a certain degree by the time the referee blew for half-time. The drama intensified over the interval as the roofless arena became shrouded in a thick winter fog.

While the low-hanging mist spoiled the view for those watching back in Ireland, inside the stadium, most of the old-school seating allowed for a decent view. Perhaps just the far corners of the ground were blurred out. The RTE television commentators, alas, were perched in the roof-top gantry - there would be an element of exaggeration no doubt.

But no embellishment was needed for the goal that remarkably put Ireland ahead in the tie as Robbie Brady broke clear, before drilling the ball low past the keeper – the Irish fans would have enjoyed a perfect view of the finish as they were packed in behind that goal.

Suddenly, the home side were shhaken and the crowd silenced, a sense of inevitability creeping in. Their team, as it happened, rallied and brought the game back to parity, the game finishing 1-1.

But for Ireland, the hard work was done.

Three days later, Martin O’Neill’s side took control early on and eased to a win thanks to two Jonathan Walters goals.

Denmark, meanwhile, were also looking to qualify for France and faced neighbours Sweden in their two-legged affair.

The Danes were also on the road for the first leg but, unlike Ireland, found themselves with a Zlatan Ibrahimovic-sized mountain to climb as they conceded either side of half-time and the Swedes took control of the tie.

Denmark battled back and grabbed a late away goal to take back to Copenhagen but they handed the initiative back to Sweden early in the second leg as that man Zlatan silenced the home support with a brace to take the tie to 4-1 on aggregate.

Despite another spirited Danish charge, their two late goals proved mere consolation.

The Danes'’ journey to this weekend’s play-off began, in earnest, that night. A new coach, Age Hareide, came in for the current campaign and naturally took time to find his feet, formation and favourite 11.

The campaign began with a whimper, with a string of average results, including a shock defeat at home to Montenegro.

However, Hareide’s side found their stride and finished on a seven-match unbeaten streak, the stand-out performance being a comprehensive 4-0 victory against a strong Poland side in September.

So both teams will look back to those play-offs as a source of inspiration ahead of this weekend’s double-header.

Denmark will vow to be better, and will have learned lessons from that disappointing defeat to their local rivals, while perhaps more importantly drawing on that recent 4-0 win, when this emerging side’s potential revealed itself.

Ireland, of course, have that winning experience under their belt and O’Neill’s settled squad will know exactly what is required to get over this final hurdle. And that just might give them the edge. All will be revealed in Copenhagen on Saturday. And then home to Dublin.