Edu Vargas struck a hat trick as Napoli thrashed AIK at the San Paolo, but Marek Hamsik was sent off.
Partenopei Coach Walter Mazzarri named an experimental lineup for the club’s opening Europa League group stage fixture.
Meanwhile, AIK Stockholm had not scored in their last four meetings with Italian sides.
Napoli took the initiative early on, and dominated the lacklustre Swedish side in the opening exchanges.
Chilean striker Vargas latched on to a long ball from Alessandro Gamberini and resisted the challenge of Helgi Danielsson before easily beating Ivan Turina in the AIK goal after six minutes.
Andreas Alms men settled in soon after that and forced Andrea Rosati to make several saves, but the Italian outfit held their own and retained their slender lead at the interval.
Vargas settled any fears of an immediate upset a mere minute into the second half. Once again Gamberini delivered a through ball for the 22-year-old to calmly double his team’s advantage.
With twenty minutes to play Vargas repaid the faith Mazzarri placed in him by sealing all three points and his hat trick.
Marek Hamsik assisted the Chilean for his third goal but was shown a straight red card only minutes later. The Slovakian had only replaced Omar El Kaddouri at half time.
Substitute Blerim Dzemaili wrapped up the scoring with a minute left from a Lorenzo Insigne assist.
Napoli 4-0 AIK
Scorers: Vargas 6, 46, 70 (N), Dzemaili 89 (N)
Napoli: Rosati; Gamberini, Fernandez, Aronica; Mesto, Donadel (Dzemaili 56), Behrami, Dossena; El Kaddouri (Hamsik 46), Insigne; Vargas (Zuinga 80)
AIK: Turina; Lorentzon, Karlsson, Majstorovic, Johansson; Lalawele, Borges, Danielsson (Lundberg 81), Mutumba (Quaison 70); Bangura, Karikari (Goitom 77)
Sending off: Hamsik 74 (N)
Ref: Turpin (FRA)