Arsenal manager Arsene Wenger has revealed that his side's 3-2 defeat at the hands of Greek side Olympiacos in the Champions League this evening was "difficult to swallow."

Goals from Theo Walcott and Alexis Sanchez couldn't stop the Gunners from losing as replacement goalkeeper David Ospina endured a difficult evening in London.

"It is still possible of course to qualify but it is difficult to swallow losing a game like that. We lost it on a lack of defensive concentration and bad luck. They had four shots on goal and we conceded three goals," Wenger told BBC Sport.

"The turning point at 2-2 is we give them a goal again straight away. If it stays 2-2 for five minutes we win the game.

"A goalkeeper can make a mistake that doesn't explain that we lose the game. It happened to Petr Cech already this season ."

The result leaves Arsenal bottom of Group F with two defeats in their opening two matches ahead of their next game in the competition against Bayern Munich on Tuesday, October 20.