Wenger bemoans Arsenal's lack of efficiency.

                

         
The hosts took advantage of a makeshift United defence to pour forward in the first half and only the excellence of visiting goalkeeper David de Gea prevented the London side from being well ahead at halftime.
But the lack of ruthlessness and the naivety which has plagued Arsenal in recent years cost them dear at the Emirates Stadium again as a second-half own goal by Kieran Gibbs and Wayne Rooney's breakaway finish gave United the points.
"We have not dominated many games against United like we did today but we were not efficient enough and made defensive mistakes," Wenger told a news conference.

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