Sagna thought the dismissal of Robin van Persie made the difference.
"We defended well as a team," the fullback told arsenal.com. "At 11 v 11 it was already difficult but after [the red card] it was impossible.
"There is not a big gap between us. They played at home so they had the ball most of the time but we needed to defend as a team like Inter Milan did last year. Conceding the goal just before half-time was bad for us - we had to come back - we did but that was not enough.
"Still we can learn a lot from them, they kept passing the ball well. We have to think about the way they played and it must be an inspiration for us."
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