Napoli midfielder Gokhan Inler feels they let themselves down after their Champions League defeat to Arsenal.
The Gunners won 2-0.
"We certainly are disappointed, but we have to look forward and not talk too much. We knew this would be a very difficult game and we have to get past it," the Swiss midfielder told Sky Sport Italia.
"In my view we lacked concentration in the opening minutes, the kind you need against Arsenal, as they start very strong.
"We tried in the second half and improved, but clearly it's very difficult to play against Arsenal, as they closed up the spaces and if you don't score then it's tough to get back into it."
