Per Mertesacker rapped Arsenal's defensive game for defeat to Tottenham.
The German says the Gunners weren't up for "proper defending" on the day.
"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 on Arsenal Player.
"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."