The Gunners head to Italy with a 2-0 lead after outplaying their Serie A opponents in the first leg at the Emirates Stadium a week ago.
"We're angry about the performance in London," he told Napoli's official website.
"We know we messed up and we're aware we didn't show our true quality. We want to do so in the return leg.
"There's still a chance we'll go through if we play as we can do, at the height of our ability. It's still open. We need to be aggressive and put pressure on Arsenal. We'll be ready on Thursday."