Arsenal manager Arsene Wenger accepts his side cannot afford many more "average" performances like against Chelsea if they are to have a say in the Premier League title race.
The Gunners went into Saturday's showdown with the leaders at the Emirates Stadium unbeaten, and holding some genuine hope of making a real impact again at the business end of the table.
However, despite creating several good openings - with Blues keeper Petr Cech denying both Lukas Podolski and Olivier Giroud, who then missed a great chance in stoppage time - Arsenal were the architects of their own downfall against a well-drilled Chelsea outfit.
Goals from Fernando Torres and Juan Mata's free-kick secured a 2-1 victory for the visitors.
And Wenger said: "We can be much better. Technically we were average, and also so was our authority at the back.
"When you play at home and concede two goals from set-pieces, it is unacceptable.
"I think there is some psychological damage because we lost the game and the players are very disappointed, especially because we have lost a game we should not have lost and that is where we have some work to do, especially in some aspects of our defensive game."
Torres had got the better of Laurent Koscielny - who retained his place ahead of Per Mertesacker as captain Thomas Vermaelen returned to the defence - to fire the visitors ahead on 20 minutes after Arsenal failed to deal with Mata's free-kick into the penalty area.
Although Gervinho levelled with well-taken equaliser just before the break, another curling deadball delivery from Mata found its way into the bottom corner on 53 minutes as Koscielny's slight deflection only helped the ball past Vito Mannone.
While Cech's reactions - particularly from a deflected Giroud shot - certainly helped earn Chelsea their fifth win from six games, Arsenal's defensive shortcomings were again highlighted.
Wenger accepted the doom-mongers would soon latch on to that well-examined area of weakness.
"I can completely understand people's opinion," he said, "but what is important is the personality you show in a big game and that is where is some areas we were not at the [right] level."
Wenger passes 16 years at the helm this week but insists for him it has always been about meeting the next challenge head-on.
"I never look back, I always look forward," he said.
"I looked at the Chelsea game and look at the next game. It is not easy, it is never easy."
Arsenal midfielder Abou Diaby limped off yesterday after less than 20 minutes.
Wenger said: "It is a thigh muscle strain. It is a minimum of three weeks."
Meanwhile, England international Jack Wilshere is expected to make his long-awaited return to action after 14 months out in an Under-21s match at West Brom on Monday.