Any defeat is not without a measure of learning though, and on a rain-lashed night in north London, two of Wenger's most influential summer signings were placed into retrospect. Arsenal were left a little fragile in a midfield devoid of Mathieu Flamini's unremitting industry and positional sense. Also missing was his ability to shield the defence, avert any potential threats and essentially shore up proceedings that might have prevented two rather soft Dortmund goals.
Arsenal's other failure was in the form of Mesut Özil. Largely subdued and denied any space to work his craft, Özil was reduced to a bit-part role in Dortmund's half. It's not as if to say Özil is solely responsible for Arsenal's creativity. But it does greatly reduce the propensity to create chances when Wenger's most potent weapon can't get anywhere near the trigger. In recent weeks, Özil has sparked the club to life, but on Tuesday night, the magic was sadly missing.
Arsenal now have it tough to get out of the Champions League's most challenging group, with precarious visits to Napoli and Dortmund still to be negotiated. Pessimists would argue that Arsenal failed their first major test of the season. But even at the cost of three points, this Arsenal team look organised, seem to have cutting-edge and know how to remain optimistic. Is this defeat the beginning of a slump? Or the springboard to a glorious season? Have your say.