Arsenal top group but Wenger's lesser lights can't find illumination
After the champagne sparkle of that stirring victory over Tottenham Hotspur, this was the annoying hangover.
Arsenal will go through as winners of Group H, in their first foray into the rebranded Europa League, but this was an unexpected, uninspiring performance which maintains Cologne's hopes of joining them in the knockout stages.
Sehrou Guirassy's second-half goal from the penalty spot inflicted a first defeat on Arsenal in Europe this season to ensure another miserable experience for Arsene Wenger on German soil. Wenger has now gone four games without a win in this country.
BATE Borisov's stalemate with Red Star Belgrade rendered the result largely irrelevant, but this was a world away from the thrilling win over Spurs last Saturday.
Danny Welbeck played 45 minutes in his first appearance since the 2-1 defeat at Watford in October and looked sharp, while there was another encouraging performance from young winger Ainsley Maitland-Niles.
But that was as good as it got, with the scenes of wild celebration at the end belonging to Cologne's supporters as they savoured what was only a second home win this season.
Wenger said: "You feel like you have done the job if you finish top of the group. I will tell you what it means after the draw, but finishing top is what we wanted.
"We have lost a game here with their only shot on goal so that is disappointing.
"It is not a penalty at all and we missed a little bit in the final third. We had plenty of dangerous situations but we always missed a little something to finish our chances.
"The pitch was a little handicap but I cannot fault the preparation or the concentration of the players."
In a lifeless first-half a below-strength Arsenal came closest to taking the lead from the most unlikely of sources.
Francis Coquelin is still waiting patiently for his first goal, nine years after making his debut, and nearly produced a Eureka moment on the half hour when unmarked in the box... but struck the post from six yards.
Cologne are currently the Bundesliga's bottom club and their game-plan was to use pace against an Arsenal back-three not renowned for mobility but counter-attacks frequently collapsed, much to the frustration of a boisterous home support.
The crucial moment came just after the hour, when Mathieu Debuchy clumsily fouled Guirassy in the area.
Guirassy, who had proved a sporadic menace, dispatched the penalty with ease and the noise was deafening, the two towers either side of the stand flashing red and white.
Arsenal did respond, with Per Mertesacker and Jack Wilshere both forcing dramatic saves from Cologne goalkeeper Timo Horn.
Reiss Nelson, an Arsenal substitute, also tested Horn as time ticked away before Wilshere was denied, again spectacularly, in added time.
© Daily Telegraph, London