The Dons take a one goal lead back to Pittodrie next Thursday after a compelling game in Reykjavik that swung one way and then the other, before a composed second half display from Aberdeen saw them recapture the lead and see out a vital win.
Returning to the stadium where Aberdeen's European adventures first began in 1967, the Dons fielded an unchanged side from that which started the 2-0 win over Dundee United on Sunday. Fit again Ryan Hedges and Dean Campbell were on the bench for Stephen Glas' team.
Their opponents came into the game in third place in their league and off the back of a 4-0 win at home to Vikingur Reyjkavik on Monday night, their fifth 4-0 win in six home games, albeit at their own stadium rather than the Laugardalsvöllur where tonight's game took place.
It was a dream start for Aberdeen, winning a third minute corner and from there, a training ground routine worked to perfection, Christian Ramirez giving his side the lead. Ramsay on the right played a low ball in from the flag kick, Scott Brown blocked off a defender to give Ramirez the room and opportunity to sweep his drive from 14 yards out into the back of the net.
The hosts had a first pop at goal on nine minutes, some neat passing play around the Aberdeen box giving Eyjólfsson a shot at goal from 20 yards but it looped harmlessly over.
It was nearly 2-0 on 10 minutes, a great ball over the top from Jay Emmanuel-Thomas setting Ramirez on his way to hit a ferocious shot from the edge of the box which the keeper did superbly to save. No matter though. Ramsay's corner in from the right found Ferguson leaping in the centre of the goal eight yards out, planting a header back across goal and perfectly placed into the top corner to double the lead.
The hosts weren't giving up the ghost and neat interplay between Vilhjálmsson and Eyjólfsson almost got Eyjólfsson in, Brown coming across to take the ball off his toe and away to safety as he prepared to shoot.
They were back in the game on 16 minutes though, Vilhjálmsson battling with Ross McCrorie on the by-line as they chased down a long ball. Vilhjálmsson got the better of it and hooked the ball across goal for Eyjólfsson to tap in from close range.
Jonny Hayes tried his luck from 40 yards out on 22 minutes, as a poor clearance reached him with the goalkeeper off his line, but there was too much loft on the club and the ball sailed over the bar.
Ramsay became the first man to go in the book for an innocuous looking foul on the half hour. The Dons were in on goal again two minutes later, lovely interplay between Emmanuel-Thomas and Ojo giving the midfielder a strike at goal that was blocked to safety.
Two minutes before the break, Ramsay slipped in trying to clear, leaving Andrew Considine to try and snuff out the danger instead, Vilhjálmsson going over his leg and winning the penalty. Vilhjálmsson sent Lewis the wrong way from the spot to level things up in the 44th minute.
HALF-TIME: BREIDABLIK 2 ABERDEEN 2
There were three changes for the Dons at the break, Hayes, Emmanuel-Thomas and Ferguson all coming off, Connor McLennan, Declan Gallagher and Dylan McGeouch replacing them, Aberdeen going to a back three.
Vilhjálmsson became the first Breidablik player to go in the book on 49 minutes after a hack on McGeouch. The free-kick came to nothing but the Dons were able to quickly get back on the attack with a long kick forward from Lewis. A magnificent first touch from McLennan killed the ball stone dead on the edge of the Breidablik area and he threaded a pass across the face of goal for Ramirez to swoop down and finish clinically for 3-2.
Vilhjálmsson produced a blatant, cynical foul on Ramsay on 53 minutes, somehow escaping the obvious second yellow card, much to the obvious frustration of Brown who wasn't shy in pointing out the severity of the offence to the referee. Muminovic did get a card on 58 minutes after he hauled down Ojo who was away on the run down the left. From the free-kick, Jack MacKenzie found Gallagher but his header was deflected, safely into the arms of Einarsson.
The Dons were looking much more composed again now, recapturing their momentum with the change of shape, McGeouch in particular dictating a better tempo to the game. A mazy run across the top of the box from Ramsay got himself in position to fire off a shot from 25 yards, not quite getting enough contact on it, the goalkeeper making a comfortable save.
Svanthorsson became the hosts first change on 65 minutes, replacing Steindórsson, while Gurr came on for Ramsay at the same time, Ramsay seemingly having taken a kick on the calf. The hosts won the softest of free-kicks 20 yards out on 71 minutes, but Gunnlaugsson got well under it, the ball flying way over the crossbar.
Fifteen minutes from time, Gurr went in the book when trying to take a throw-in, though even after Stephen Glass had a lengthy chat with the referee, nobody was any the wiser as to why. With time running out, Yeoman and Mikkelsen came on for Eyjólfsson and Sigurjónsson on 82 minutes, Hedges replacing Ramirez for the Dons at the same time.
Ojo could have sealed things on 87 minutes, McLennan doing well down the right before pulling the ball back to Gurr. His cross found Ojo at the back post with just the goalkeeper to beat, but he headed into the ground and gave the goalkeeper an easy save.
Atlason joined the fray on 88 minutes in place of Sigurdarson as the home side desperately looked for an equaliser, but Aberdeen were looking a far more settled side defensively in the second half, leaving Lewis very much a bystander.
Ingvarsson absolutely poleaxed Gurr as the game edged into added time and was perhaps fortunate to come away with no more than a yellow card, the final action of what was ultimately a very satisfactory night for the Dons.