The shock win brings the Sicilians level on points with Napoli.
"We are doing very well, this is a great club and the players are expressing themselves at a high level," said Montella of their 2-1 victory.
"The negative aspect is that we really suffered under pressure towards the end. We were playing against 10 men and should've finished the game off a lot earlier. We could've dealt with the situation better."
The Elefantini have made a habit of fighting back to get a result this season and were 1-0 down to Napoli after just 30 seconds.
"We seem to go into the players' tunnel five minutes early, the tension drops and we concede a goal early on.
"Being so high up the table looks a bit like a joke, as usually we have it upside down, but don't forget we are targeting safety and must maintain our objectives. Having said that, next up is Milan and our first away win would be the icing on the cake."