Arsene Wenger lamented Arsenal's defending as two goals in two first half minutes consigned his side to a 2-1 derby defeat to North London rivals Tottenham.
Arsenal's defensive line was breached twice in quick succession as, first Gareth Bale, then Aaron Lennon raced onto through balls to slot past Wojciech Szczesny.
The visitors pulled one back when Per Mertesacker's header flicked off Bale and into the net but Tottenham held on to open up a seven point gap to their rivals.
Wenger said Arsenal were sloppy at both ends of the field but rejected suggestions that Tottenham were now the top side in north London.
"That's not the impression I got from the game today,'' he said on Sky Sports. "We were not efficient in those decisive zones, not at the back or up front. We were not cautious enough. On the two goals we played offside in a position where we shouldn't play offside.''
He did, however, praise the effort his side put in believing it deserved a more positive outcome. "It is difficult to struggle with defeat because of the effort we put in and the energy level we put in over the 90 minutes was tremendous,'' he added.
"We made it difficult for ourselves. We came back and dominated the game but the game was stop and go. It was difficult to get a flow in the final 20 minutes, we didn't find the second goal.''
Wenger vowed that his side will not give up chasing a Champions League spot for next season. "It's very frustrating, but we have to put the energy in every game like we did today and keep going, you never know.
"It would be absolutely terrible not to fight like mad because there is a lot of positives in the game. What happened today we have seen repeated so many times in big games that of course it's difficult.''
Reports this morning suggested a Middle East consortium was interested in investing in the club, but Wenger would not be drawn when asked what he knew.
"Nothing,'' he said. "If people are ready to invest their money it means the club is not moving too much in a bad direction. I am nothing to do with it. I focus on my job, financial is down to the directors, shareholders and the owners.''
Information from the Press Association was used in this report