Napoli and Inter Milan have scored five goals between them in a rip-roaring first half at the Stadio San Paolo in Naples.
It was Gonzalo Higuain who opened the scoring after eight minutes, firing a volley past Samir Handanovic after Yuto Nagatomo failed to clear his lines with a header.
Lorenzo Insigne nearly doubled the lead in the 25th minute, but his shot rattled the post.
Walter Mazzarri's men struck back in the 34th minute when Esteban Cambiasso nodded in at the far post, but the Nerazzurri were left stunned when Dries Mertens restored the Partenopei's lead with a curling effort five minutes later.
Blerim Dzemaili then gave Rafael Benitez's side some breathing space just before half time, but that was quickly eroded by Nagotomo.
