Arsene Wenger admitted it was frustrating to lose another big game following Arsenal's defeat at White Hart Lane but rejected suggestions that Tottenham Hotspur were now the top team in North London.
Spurs had offered little as an attacking force before goals from Gareth Bale and Aaron Lennon in a decisive spell just before half-time.
The Gunners pulled a goal back when Per Mertesacker's header was deflected in but they could not salvage a point and Wenger was again left to bemoan defensive mistakes.
"It is difficult to swallow a defeat like that because of the effort we put in," he told Sky Sports.
"We made it difficult for ourselves. They had no shots on goal and then we were down 2-0. "We came back in the second half and dominated the game again, but it was difficult to get a flow in the final 20 minutes because there were a lot of stops and we didn't find a second goal."
The result left Arsenal five points adrift of fourth-placed Chelsea and seven behind Spurs, but Wenger is refusing to give up in the battle for Champions League qualification.
He said: "It is very frustrating but we have to put the energy in like we did today and keep going and 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."
Questioned on whether there had been a power shift in North London, Wenger replied: "That's not the impression I got from the game today.
"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."