Ranieri's first game in charge at the San Siro ended in defeat, as goals from Campagnaro, Mascara and Hamsik condemned the Nerazzuri to another home disappointment
Claudio Ranieri's home debut as Inter coach ended in embarrassment, as goals from Campagnaro, Mascara and Hamsik gave Napoli a 3-0 victory and extended the Milanese club's shocking home record this season.
Red cards for Joel Obi and Ranieri himself mean the 2010 treble winners are still without a win, or even a goal, at the San Siro this campaign.
The main news going into the game for Napoli fans was the absence of top-scorer Edison Cavani through injury. Goran Pandev being drafted in as his replacement, in an otherwise unchanged side.
For Inter however, it was the inclusion of Giampaolo Pazzini that was the main surprise. Having been declared injured throughout the week, his involvement, in place of Mauro Zarate, was a huge and uplifting shock for the Interistas.
And it looked as if Ranieri had pulled off a masterstroke on 23 minutes. The surprise starter Pazzini pouncing on a spilt ball from De Sanctis to tap in from three yards. Unfortunately for Inter, Pazzini was judged as offside and the goal was, rightly, disallowed.
The match was being played at an almost Premier League tempo. Both sides were going for broke, but that certainly didn't equal a host of chances. Lavezzi perhaps had the best of them: a cross from Juan Zuniga found the Argentinian who had his glancing header saved by Julio Cesar on 30 minutes.
The deadlock was broken though 40 minutes. A superb run down the right-hand side by Christian Maggio was halted by Joel Obi, who was adjudged to have pushed the central-midfielder inside the box. A penalty was given and a second yellow card brandished to the Nigerian. The resulting penalty from Marek Hamsik was saved, but Hugo Campagnaro was there to fire in the rebound and give the Partenopei a 1-0 lead at half time.
That man advantage was starting to show after the break, and substitute Giuseppe Mascara reinforced Napoli's dominance on 55 minutes. Hesitation from Nagatomo meant Mascara could nip in 18 yards out, and chip the ball over the on-rushing Julio Cesar to give the visitors a two-goal advantage.
And things got even better for the southerners on 75 minutes. A through-ball from Lavezzi dissected the Inter defence, and Marek Hamsik was on hand to calmly slot the ball into the net from 12 yards out.
The win leaves Napoli top of the table on 10 points. Whilst Inter languish just outside the drop-zone on four.