Napoli fought back from 2-0 down to win 3-2 on Saturday.
"We went behind, but knew that we could do better and had more scoring opportunities than Milan, but they converted both their chances," the defender told Radio Kiss Kiss.
“After it went to 2-0, we had nothing more to lose and had a strong reaction. We will go far with this group and this mentality.
“I don't think David Ospina ever made a save, but we've still got to work hard and ensure we don't keep conceding at the first opportunity."
He added: "You can tell that we trust each other and have been together for many years. We know that we can turn situations around, but at the same time shouldn't get ourselves in those positions in the first place."