Arsenal manager Arsene Wenger has refused to discuss the reasons behind the decision start David Ospina instead of Petr Cech for the Champions League defeat to Olympiakos. Ospina's clanger which gave the Greek champions the lead for the second time contributed to seeing the Gunners drop to the bottom of Group G after a 3-2 loss at The Emirates Stadium.

Cech was the club's only signing during the summer transfer window but he was omitted for a second European game in succession, but the decision to start Ospina would come back to haunt Wenger. After Theo Walcott had cancelled out Felipe Pardo's deflected opener, Ospina dropped Kostas Fortunes' corner into his own net and leaves their European hopes in tatters.

But Wenger has refrained from going into detail regarding the decision-making process but he did reveal that Cech was suffering from a slight injury suffered before the Premier League win at Leicester City. [To Blame Ospina] that is always the simple thing," the Arsenal boss snapped. "Ospina played 19 games last year, kept 14 clean sheets and last week at Tottenham he has a fantastic game. Goalkeepers make mistakes, it could have happened to Petr Cech as well. It is part of it.

"I do not have to explain why. I do not have to sit here an give you an explanation about every decision that I make. [Cech] had a slight alert before the game at Leicester; I didn't want to take the gamble. It is not because of that, that we lost the game.

"I make the decisions and the selections for the team and I know many things that you don't know and that maybe you ignore. I do not select the team by getting a poll before the game and getting everyone's opinion."

The result leaves Arsenal without a point from their opening two group matches ahead of facing Bayern Munich, who are top are thrashing Dynamo Zagreb 5-0. Wenger says successive defeats leaves his side in a "bad position" but he remains optimistic.

"It leaves us in a bad position but we are still in it," he stated. "We have to of course think that we can deal with Zagreb and Olympiakos and we have to make a result in our next game against Bayern at home. We are not out of it."

A first ever defeat on match day two for Arsenal in the Champions League was compounded by injury to Laurent Koscielny, who was replaced by Per Meretsacker after 57 minutes, who is now a doubt for the visit of Manchester United on Sunday [4 October].

"It is a hamstring, it looks to be a hamstring," Wenger revealed. "We play many games and that is why we rotate as well. You look at the benches of the other teams in the Champions League they rotate their players, you cannot play every three days without rotating your players that is a fact and we have to accept that."

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