Livorno have sent last year's Coppa Italia finalists Sampdoria out of this year's competition with a surprise 2-1 comeback win in the fourth round, while Triestina edged an all-Serie B clash.
Sampdoria, who won their fourth and last cup 15 years ago, are currently flying high in Serie A this season, but Luigi Del Neri's side were seeking a boost after suffering a 3-0 reverse against derby rivals Genoa at the weekend.
With Livorno languishing in the relegation places, not many were tipping the Amaranto to progress on their travel to the Stadio Luigi Ferraris.
And it seemed as though the visitors' involvement in the cup would come to an end when Daniele Mannini opened the scoring for Samp after 46 minutes, but a second-half double by Tomas Danilevicicus put paid to that notion.
Danilevicicus grabbed the equaliser, which deflected off Stefano Lucchini, after 76 minutes before the Lithuanian striker grabbed the winner 10 minutes later to send the away fans into raptures and book a fifth round clash with Inter.
In the evening's other match, Marko Stankovic's second-half strike saw Triestina into the last 16 as they dumped Sassuolo out of the competition.
The 23-year-old Austrian striker broke the deadlock after 57 minutes and it proved decisive as the Unione edged out their Serie B rivals to set up a meeting with Roma in the next round, where the top eight Serie A seeds enter the competition.
Catania host second division Empoli on Wednesday in the final tie of the fourth round, while the one-legged last 16 matches take place over December and January.
Fourth Round Results
Wednesday 25 November 2009
Chievo 2-0 Frosinone
Siena 0-2 Novara
Thursday 26 November 2009
Atalanta 0-1 Lumezzane
Napoli 1-0 Cittadella
Palermo 4-1 Reggina
Tuesday 1 December 2009
Triestina 1-0 Sassuolo
Sampdoria 1-2 Livorno
Fourth Round Fixtures
Wednesday 2 December 2009
Catania v Empoli (1400)
Fifth Round Draw
10, 15 December 2009, 13 January 2010
Fiorentina v Chievo
Lazio v Palermo
Juventus v Napoli
Inter v Livorno
Milan v Novara
Udinese v Lumezzane
Roma v Triestina
Genoa v Catania/Empoli
* All kick-off times listed are UK time (+1 for Italy/CET). Times, dates and fixtures are subject to change.
Coppa Italia Fourth Round Reviews
[25 Nov 2009] - [26 Nov 2009] - [1 Dec 2009] - [2 Dec 2009]
Source: Sky Sports