Manchester City managed to beat United 6-1 at Old Trafford on Sunday, while Arsenal lost 8-2 to United less than two months ago.
“It’s a surprise,” Wenger said. “But France nearly beat New Zealand in the rugby (World Cup final) and that was a surprise.
“Like when we lost 8-2, the big scores have no special meaning, it only means something special happened in the game.
“When you are in a position where you have to attack with 10 men against a good side you are vulnerable. It’s not that you lost three points, but the emotional aspect of a result like that remains in your head.”
