Atalanta coach Gian Piero Gasperini says they must learn from their 5-0 home thumping by Liverpool.
Diogo Jota, with a hat-trick, Sadio Mane and Mohamed Salah struck the goals for the Reds in this Champions League group fixture.
“We have to reflect, because we lost badly in Manchester last season, but were confident we could change a few things and make a big difference," Gasperini told Sky Sport Italia.
“Tonight, there really was a big gap and we have to reflect on the tactical and structural approach for matches like this, otherwise it becomes very difficult indeed.
“We had no fear of Liverpool, as we were coming off two good results, so there was no fear. We played Liverpool with the confidence we usually do, sure we could create them problems and hold out under pressure.
“Unfortunately, they blew us out of the water in terms of intensity. I've seen it before this season in Serie A too, we don't have the intensity we did in the past and have to change our syle a little bit to compensate for that.
“We struggle to maintain the pace we did in the past, in Serie A and the Champions League, so we need to make some modifications and change the way we play."
He added: “As I said, we learned from the City result, we had a beating against Inter a few years ago and found a solution after that. Hopefully this can be another teachable moment.
“Playing every week in the Champions League is tough when there's a game every three days, then we have very tough fixtures in Serie A too, so it's tough on all of us in those tournaments, like Juventus, Inter and Lazio. That's something the teams in the Cups have to deal with and accept."
