Arsenal boss Arsene Wenger admits their defending has been poor this season.
Arsenal face Sunderland, who have their own questions to answer at the back after losing 8-0 to Southampton, at the Stadium of Light.
Wenger said: "At the moment, yes [defending is our weak link].
"Last year we had 17 clean sheets and at the moment, we've only had one after eight games. That's something that we are not on the same level defensively.
"It will improve by getting everybody to put a bit more effort in to the defensive work. That starts not only at the back, but up front and in midfield by increasing the level of defensive activity through the team. We had to reshuffle the defence and [the players] getting used to playing together helps as well."
