Arsenal boss Arsene Wenger admits they must tighten up at the back to beat Manchester United on Sunday.

Wenger was particularly unhappy with the nature of Swansea's third goal, which came almost immediately after Theo Walcott had equalised at the Liberty Stadium.

"You will never find a happy manager after a defeat like that. What was worrying was that while we were 1-0 up we had chances to score the second goal and then we gave goals away," he told Arsenal Player.

"We thought we had stabilised the defensive sector but we have been vulnerable in recent games. When you come back to 2-2 and then 30 seconds later it is 3-2, it is very difficult to swallow.

"The team has been very disappointed but I cannot fault the effort. If we score two goals away from home we must be capable of coming away with a point at least. That is where we want to improve and come back to our defensive stability."