Catania needed a last-gasp goal to force nine-man Cittadella into extra time, eventually winning 3-1 to set up a clash with Parma.
The Sicilians were almost given a very rude awakening at the Massimino this afternoon, as Serie B team Cittadella wasted several great opportunities in the first half and missed a penalty with Bellazzini firing wide.
Despite all those errors, Cittadella still went in front before the break thanks to a Paolucci curling free kick.
Busellato received a second yellow card for a handling offence on 51 minutes, followed at the 68th by teammate De Vito.
Even down to nine men for the last 22 minutes, Cittadella clung on thanks to the remarkable saves of 43-year-old goalkeeper Pierobon.
However, in the final minutes Gonzalo Bergessio was able to get the decisive equaliser from close range.
Extra time was a miracle too far for Cittadella, who capitulated 3-1 after Francesco Lodi’s free kick and a Bergessio header.
Catania scrape through to the Fifth Round, where they will face Parma at the Stadio Tardini.