Szczesny came off his line before tripping Yilmaz as he advanced on goal when Arsenal were leading by four but Wenger feels it was a clear lack of concentration by the whole team which led to Galatasaray's goal.
"It's a fraction of a second," he told told Sky Sports 1 in relation to the incident which resulted in Yilmaz beating substitute keeper David Ospina from the spot.
"He has to come out and he makes a penalty.
"I felt when you lose the ball in your own half like we did that kind of thing can happen.
"That's the problem at that level, it's Champions League and you can only keep consistent domination of a game if you keep your concentration and we just relaxed a little bit with the fourth goal."
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