Naples, Jan 3 (IANS): Atalanta stunned Napoli 2-1 here to advance to the semi-finals of the Coppa Italia football tournament for the first time in 21 years.

Timothy Castagne (30th minute) and Alejandro "Papu" Gomez scored for the visitors while substitute Dries Mertens pulled one back for Napoli on Tuesday night.

Gian Piero Gasperini-coached Atalanta pressed throughout the first half, disrupting the usually high-powered Napoli attack, without regulars Lorenzo Insigne and Mertens, reports Efe.

Atalanta limited the hosts to a single chance, a botched attempt by Piotr Zielinski in the 30th minute.

Castagne put the Bergamo club ahead 1-0 with a goal in the 50th minute. Andreas Cornelius controlled a Gomez cross and Castagne fired into the roof of the net from the right post.

Gomez doubled Atalanta's lead in the 81st minute as he charged past Vlad Chiriches on the left flank before holding off central defender Kalidou Koulibaly and blasting into the far top corner from a tight angle.

With their backs against the wall at home, Napoli threw everyone forward and the effort paid off in the 85th minute as Belgian forward Mertens exploited a poor clearance by Atalanta goalkeeper Etrit Berisha to cut the deficit in half.

But it wasn't enough to spare Maurizio Sarri-coached Napoli from an embarrassing second elimination of the season after failing to qualify for the knockout stage of the Champions League.

Atalanta's semi-final opponent will be the winner of Wednesday's Juventus-Torino clash. The other semi-final pits Lazio against AC Milan.