Napoli crash out of Coppa Italia after shock Frosinone thrashing
Quickfire goals by Enzo Barrenechea and Giuseppe Caso in the second half put Serie A side Frosinone in front before another two strikes in stoppage time sealed their place in the quarter-finals.
Napoli thought they had opened the scoring late in the first half through forward Giovanni Simeone but the goal was ruled out for a handball in the buildup.
While the hosts struggled to create scoring opportunities, Frosinone, who were playing in the last 16 for the first time in their history, took a surprise lead in the 65th minute when Barrenechea headed home a corner and Caso doubled their advantage five minutes later with an individual effort.
Frosinone, currently 13th in the league, made it 3-0 through Walid Cheddira from the penalty spot after Giovanni Di Lorenzo fouled Francesco Gelli and Abdou Harroui sealed the win for the visitors late in stoppage time.
Napoli had won all their previous six matches against Frosinone in all competitions.