Monday 9 February 2015 08:28, UK
Per Mertesacker accepts Arsenal were “not switched on” during the derby defeat to Tottenham on Saturday.
The Gunners took the lead through Mesut Ozil after only 11 minutes at White Hart Lane but Harry Kane scored twice to settle the contest in the home side’s favour.
His second goal came with just four minutes of the game left and the scoreline meant Arsenal ended a run of three successive clean sheets.
Mertesacker admits it was a backwards step for Arsenal, who are sixth in the Premier League and a point behind Spurs.
"We found a way recently to prepare ourselves on crosses better defensively (and also) on set-pieces, but we did not switch on quickly enough and were not up for proper defending, so that was worse than in recent weeks," Mertesacker said.
"We were not active enough and only started to play our game a bit towards the end, that took us too long.
"When we had the ball, we could not find any solutions, they were always at us and we could not get the ball quickly in our own half so we could not hurt them on the counter-attack."
The German, who is captaining the side with midfielder Mikel Arteta still injured, added: "We have to analyse the problems they caused us, then we focus on Tuesday to bounce back from this setback as quickly as possible."
Arsenal manager Arsene Wenger also admitted his side made "too many technical mistakes in the middle of the park" and was also less than impressed at the way Spurs crafted a late winner.
He said: "(For the second goal) Kane had a completely free header in the box, with five minutes to go, that is difficult to understand with the experience we have at the back.
"I am disappointed by the quality of our football and it was just not good enough."
