The decisive goalscorer had some eye-opening words for the Gunners after their defeat.
With other English sides also experiencing struggles in the Champions League, the criticism has been understandably rife, and particularly so for the Gunners.
Alfred Finnbogason was the man who condemned Arsenal to defeat on the night; his late goal giving Olympiakos the late edge in the game. And now he's moved to rub further salt in opposition wounds.
Speaking after the game, as reported by the Guardian, the Icelandic striker insisted that his team were aware of Arsenal's tendencies to shirk the defensive side of the game.
"When you play against this team you know they're going to have a lot of the ball," Finbogasson said. "You have to defend well, have the lines tight and use your time when you have spaces. And you know you're going to have spaces because they don't want to defend. So our plan worked."
The stinging defeat condemns Arsenal to the bottom of Group F after two games, while next up for them in the competition is the sizable challenge of Bayern Munich, who are quite arguably the tournament's standout team at present.
But until then, Arsenal will need to get back on track in the Premier League, and the prospects of that don't appear to be easy either. They host leaders Manchester United this weekend, in a game that will affect their season significantly in one way or another.