Arsenal will tell themselves this was not a do-or-die fixture. Qualification for the Champions League's knockout phase had already been assured and the merits of advancing as the group winners to the last 16 remain dubious. Scary fish are circling in the pot of runners-up. Arsène Wenger's starting XI had also been experimental.
Yet the manner of the defeat by Greece's champions raised familiar questions, which Wenger is sick of hearing let alone addressing. A goal up at the interval, courtesy of a slick assist from Gervinho and a thumping conversion by Tomas Rosicky, on only his second appearance of the season, the scene had been set for Arsenal to show steeliness and professionalism, to slam the door on any Olympiakos fightback.
Instead, the hosts took a grip on proceedings and they floored Arsenal with two goals in quick succession. Wenger raged about the first, scrambled in by Giannis Maniatis, which followed the award of corner that should not have been. Wojciech Szczesny did not get a hand on Paulo Machado's header, which kissed the post and went out, and the goalkeeper said that the additional assistant referee had told him it was to be a goal kick. Why did he not tell the referee? At full-time there was the now standard sight of Wenger remonstrating with a fourth official on a European night.
But Arsenal could have no complaints about the result and it was merely worrying to witness how sharply the tide turned in the second-half, and how they lacked the collective strength of character to halt it. With Montpellier holding Schalke, Arsenal spurned the opportunity to leapfrog the Germans but, more importantly, there would be no soothing tonic after the disastrous home defeat by Swansea City in the Premier League and ahead of the vital visit of West Bromwich Albion.
"We need a good Christmas present," Wenger said, with a nod towards the last 16 draw on 20 December. "The disadvantage is that we have to play the second game away, although it's not statistically proven that it's a disadvantage. The important thing now is to focus on the championship and get ourselves back in decent form."
This was Wenger's 150th game in the Champions League but it had felt like a time for scrutiny rather than appreciation. The buildup had in effect been an argument between the manager and the critics, with the former, uncharacteristically, reacting with hostility and scarcely concealed contempt to those who questioned him. Wenger railed against what he called "superficial analysis" from some pundits but it was clear that the hard currency of a positive result was in order.
Wenger may have dreamed of his team scoring the opening goal to fire the confidence levels and he was left to curse a gilt-edged early miss by Aaron Ramsey. After Marouane Chamakh had headed down Alex Oxlade-Chamberlain's cross and Drissa Diakité failed to clear, the ball sat invitingly for Ramsey, close to the penalty spot, only for him to miss his kick completely. Earlier, Oxlade-Chamberlain had dragged a shot so far wide that it went out for a throw-in. Arsenal had looked disjointed.
But, with Olympiakos having grown into the tie and enjoying the better of first-half chances, Wenger's team struck, following their first contribution of quality. Gervinho surged to the byline, jinked sharply to throw his markers and rolled the perfect cut-back into the path of the onrushing Rosicky. His side-footed finish was laced with power and precision. Arsenal had laid the foundation stone for the victory.
Olympiakos flickered as an attacking force in the first half, with the impressive Djamel Abdoun delighting with his skill and vision. His best first-half moment saw him spin away from challengers and threaten the edge of Arsenal's area before offloading to Vassilis Torossidis. The marauding full-back's shot was high. Abdoun almost set up Rafik Djebbour only for Thomas Vermaelen to intervene while Torossidis went close with a header and Abdoun brought a smart save out of Szczesny.
Wenger said that it was always the plan to withdraw Rosicky at half-time and his replacement, Andrey Arshavin, twice went close. There was a sight for sore eyes when the eternally frustrating Chamakh crossed and Arshavin headed wide while the Russian drew a reaction stop from Roy Carroll. Arsenal grew nervous and Olympiakos sensed their opportunity. Ljubomir Fejsa had swelled the side-netting when Machado, completely unmarked, produced a header that had Szczesny scrambling across his line. The corner was given, despite Arsenal's complaints and, when Abdoun returned the ball after it had been half-cleared, Kostas Manolas's header struck Ramsey before breaking for Maniatis, who bundled home.
"It was a very bad decision," Wenger said. "You would like for the fifth referee to be concentrated on their job but it was not the case. We have to take it on the chin and focus on our next game."
Arsenal's focus deserted them. The unmarked Djebbour planted a stooping header wide from Machado's cross and an Olympiakos winner had been advertised. It came when one of the three attack-minded substitutes, Kostas Mitroglou, curled a right-foot shot towards the far post. It kept on going, through a crowded area, past Szczesny and into the corner. Arsenal had that sinking feeling.