The fairytale lasted 42 minutes until reality kicked in.
Finally, Arsenal decided enough was enough and they blitzed Dundalk with three goals in the space of four minutes either side of half time.
It was hardly a vintage European performance for Mikel Arteta’s men but certainly a night the League of Ireland minnows will never forget even it would have been so different with a full crowd at the Emirates.
That is the beauty of these nights and why Europe’s elite should never be allowed to spoil these stories and adventures and the romance of a David v Goliath battle.
Eddie Nketiah, man-of-the-match Joe Willock and Nicolas Pepe were on target for Arsenal as their quality was too much when, sadly, Dundalk keeper Gary Rogers looked more Sunday League than Europa League.
Rogers fumbled and dropped his way through the game which turned into a precession for Arsenal even if Arteta had made 10 changes to rest players for Sunday’s trip to Manchester United.
But you could see Arteta’s face turn to thunder in the opening half hour as Arsenal struggled to find a way past Dundalk’s brave resistance.
Pepe was as frustrating as anyone as, at times, you wonder what on earth possessed Arsenal to pay £72m for someone who is ultimately a squad player.
Then he goes and turns on some style to produce a wonderful goal for Arsenal’s third, curling in a shot with his right foot – his wrong foot – from the edge of the box.
There is definitely a player in there somewhere, who can dribble, pass and take a free kick but you suspect that Arteta will have to be at his very best to get the best from Pepe’s huge potential.
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But Willock was excellent, even against lesser opposition it is obvious he is a terrific young talent who can break forward from midfield, unlock defences and score goals.
Nketiah, too, despite a terrible miss before scoring his typical poacher’s goal, has now got five goals in all competitions and has scored in every competition he has played in.
It was hardly a performance and victory to write home about or get carried away with but it is now two straight wins and, with bigger games ahead, no more added to a growing injury list.
Arteta certainly could not have afforded a slip-up and debutant keeper Alex Runarsson, was the first to make a decent save as he pushed Patrick McEleney’s low shot round the post.
But from then on, Arsenal pressed back the visitors but just could not find a way through.
Error-prone Rogers fumbled Sead Kolasinac’s shot over the bar before Nketiah missed a gilt edged chance from inside the six yard box.
Finally, Arsenal got the breakthrough after 42 minutes when Dundalk’s defence fell apart from a Ryan Nelson corner.
Keeper Rogers messed up again, the ball bounced off Daniel Cleary and then Nketiah forced home from close range.
Two minutes later, it was game over if it was ever a contest. Pepe’s shot was blocked, the ball fell to Willock and he smashed home into the net.
Within a minute of the restart, Pepe made it three. Willock played it into the Ivory Coast winger who took the shot early and Pepe curled a right-footed effort into the top corner from the edge of the box.
It was almost rolling subs in the second half and Arsenal could have added more but Dundalk somehow did not concede any more to stop it turning into a rout.