Genaro Gattuso’s southerners were four goals up at halftime in their Diego Armando Maradona Stadium, before the visitors pulled two goals back in a three-minute second half spell.

Senegalese defender Kalidou Koulibaly got the first after five minutes with a backheel kickoff an Elseid Hysaj cross.

Piotr Zielinski sent over the top for Hirving Lozano to fire in the second on 20 minutes with the Polish midfielder involved in Matteo Politano’s third goal on the half hour.

Lorenzo Insigne missed a chance before setting up the fourth with Eljif Elmas beating Spezia goalkeeper Titas Krapikas minutes before the break.

Vincenzo Italiano’s Serie A newcomers, who shocked Roma in the last 16 and beat Napoli at home in the league earlier this month, fought back.

Gennaro Acampora teed up Emanuel Gyasi to slide into goal after 70 minutes, with the former Napoli youth player then scoring himself with a low shot from outside the area past a static David Ospina.

Napoli next play Atalanta with Inter Milan taking on Juventus in the other semifinal which will be played over two legs on Feb 3 and 10.