The excerpt from "The Cask of Amontillado" that best infers what will be Fortunato's downfall is that despite knowing he was, respected man had his weak point and because of this he prides himself on connoisseurship.
Fortunato is described as being selfish and greedy; this is the reason why he will fall without having Montresor nor Luchesi to bring him down. Even though he keeps on trying to show how better, he is than Luchesi. The main reason for doing this is to ensure Lucheso does not touch Amontillado.
