A fatal dash from his line cost Arsenal the second goal, albeit Cristiano Ronaldo's tap-in also coming courtesy of a lightning United move.

Several more rushes of blood when Almunia went AWOL from his six-yard box spread confusion in an otherwise robust defence.

Wenger said: "He rushed out to block the cross and he was unhappy with his decision making. Would he have caught the ball? Could he have stayed inside? He left his goal and didn't get the ball so he'll feel as if he made a mistake. I'll have to watch it again."

When he does he might rue his decision to stick by Almunia ahead of Jens Lehmann, a player with vastly more experience if one also not unaccustomed to the odd aberration.

Wenger explained: "Lehmann was injured and Almunia has done extremely well since, 10 games on the trot. I didn't want to disturb the side.

"Until now, he has done very well. I believe in sticking with one goalkeeper. You cannot tell him: 'No matter how many mistakes you make, you'll always be my goalkeeper.' But you have to give him at least two games."