Although Czech midfielder Tomas Rosicky fired the English side ahead on 38 minutes, the Greeks fought back through a somewhat controversial effort by Giannis Maniatis and a well-taken strike from substitute Kostas Mitroglou to leave Wenger facing more questions about the direction of his team - who have now not won in the last four and plummeted down the Premier League table.

Defeat in the Georgios Karaiskakis Stadium for a second successive season coupled with Schalke's draw in Montpellier means Arsenal will head into the knockout stages without the security of a top seeding.

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Wenger, though, is not overly concerned. He said: "We need a good Christmas present now (in the draw), but we will see.

"We can get a bad draw or less strong team, but you normally get strong teams through anyway now.

"The disadvantage is we have is we play the second game away, but that is not statistically proven to be a such a disadvantage.

"Let's see, but for now it is important for us to focus on the [domestic] championship, forget about the Champions League a little bit and get ourselves back in decent form in the championship."

Wenger tried to remain upbeat despite the disappointing final outcome in Athens.

"We left eight or nine players at home and we had a positive game," he said.

"We had a good first half, but we dropped physically in the second half because many players lack competition at that level and therefore we couldn't take the chances for the second goal.

"We also got a very bad decision against us on the goal. I am not against the fifth referee, but you would like at least for them to be concentrated on their job, but that was not the case tonight, Wojciech Szczesny was far away from the ball.

"Why didn't the fifth official tell the referee? It's difficult to understand, to concede a corner when it doesn't go off the goalkeeper.

"However, I don't want to make a fuss of it, so we have to take it on the chin and go home and focus on our next game."

Rosicky had just come back from an injury lay-off, and Wenger revealed his second-half substitution was pre-planned.

He said: "Tomas has not played for six months and we were cautious with him.

"We decided before the game to play for 45 minutes and see how he got on. He is a bit tight, muscular, but no [new] injury.

"We will see how we recovers now for Saturday."

Meade was replaced by 18-year-old Swiss defender Martin Angha for the closing stages, and Wenger feels it would have been a good experience for the duo, but hinted he could yet look for reinforcements when the transfer window opens.

"I feel the young players, you discover them in these kind of competitions we had tonight. They have the quality," he said.

"If everybody is fit we have a strong squad, but in certain areas we are a bit short because we cannot rotate.

"We will see where we stand on January 1 and see what we do."

Arsenal, who were beaten 2-0 at the Emirates last weekend, host fifth-placed West Brom on Saturday.

Wenger challenged his team to produce a response.

He said: "It is a good opportunity for us to keep focussed, to show strength and unity, that is what you want to do in the next game."

Olympiacos coach Leonardo Jardim, meanwhile, must now prepare his side for the Europa League, having in the end finished only one point behind Arsenal.

The Portuguese said: "We are not happy that we missed out on our goal of qualification for the knockout stage of the Champions League, however we knew that before tonight.

"We just had to focus on getting the win, to become one of the top seeds for the Europa League and to play well in front of our fans, so I am pleased we achieved both of these aims."