Jens Lehmann kept goal as Arsenal secured their ninth consecutive Champions League clean sheet in the 1-0 Semi Final first-leg win over Villarreal on Wednesday evening.
The result leaves the Gunners needing just a draw or a one-goal defeat, other than 1-0, to progress to the next month's Final in Paris. But the new German No 1 believes both he, and his team-mates, must improve for the return leg in Spain on Tuesday.
"In the first leg we have a result which is not bad - it could have been better but could have been worse," said Lehmann.
"At this level, in the Semi Final, any little mistake could knock you out so we can't afford that, we have to improve. Personally, I always think I can improve and I think everybody can. You can always improve a little bit. So the main goal now is to go the Final."
Lehmann revealed how he shouts at his defenders to keep them on their toes and commended them for their efforts during the Gunners' eye-catching run to the brink of the next month's showpiece in Paris.
"Of course they are doing a great job," he said. "You have to keep them awake, but I feel it's not easy for a defender to have to concentrate for 90 minutes and you can't afford to make a mistake.
"Probably sometimes it helps when somebody is shouting."
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