Arsene Wenger has admitted that Arsenal's new defence lineup has not yet learned to work well as a unit.
The London club currently sit in 17th place in the Premier League with four points, having conceded 15 goals.
Following an 8-2 loss to Manchester United, on Saturday the Gunners gifted Blackburn Rovers a 4-3 win by conceding two own goals.
"Andre Santos and Per Mertesacker are new, but they were not especially guilty on the goals. But maybe as a unit we need more time to work," he told Arsenal's official website.
“A lack of concentration, a lack of communication, a lack of coordination and individual urgency [is behind the goals we have conceded].
"When you score an own goal, you have to look at yourself. It is never completely out of your reach where you have no chance at all. All the rest, you have to look at yourself.”
Arsenal face Shrewsbury in the Carling Cup tonight (Tuesday), before continuing their Premier League campaign on Saturday at home against Bolton.