Wenger said: "For the goal, he was calculating on the cross and it is like what happened to David Seaman on Ronaldinho's free-kick.
"If he hadn't come for the cross you say 'what is he doing on his goal-line' and he was unlucky that the ball headed towards the top corner.
"For me, it is not a massive mistake because I like the guy who likes to step out on the cross.
"I don't like the guy who stays on the line and says 'I make no mistakes'. I prefer to be caught once like that and be caught once out of 100, rather than playing completely safe on the line."