El Matador has reached the impressive milestone in less than three seasons and it's his third treble this season against three sides currently in the top eight -both Rome clubs being the others. Napoli are now unbeaten in this fixture since October 1997, earning five wins and two draws. With just three games left to play, Napoli move seven points clear of third placed AC Milan, while Inter trail the Europa League places by five points.
Inter came into the game on the back of five defeats in seven and an ever growing injury list. In addition to Luca Castellazzi, Ibrahima Mbaye, Javier Zanetti, Matias Silvestre, Yuto Nagatomo, Walter Samuel, Dejan Stankovic, Walter Gargano, Gaby Mudingayi, Joel Obi, Diego Milito, Rodrigo Palacio and Antonio Cassano, veteran frontman Tommaso Rocchi pulled out with a knock to leave Andrea Stramaccioni with no recognised strikers.
It took Napoli just three minutes to hit the front. Pandev threaded through for Cavani to blast the ball home from six yards, giving Samir Handanovic no chance.
The visitors came close to an instant reply after Morgan De Sanctis parried Guarin's vicious free-kick and Juan Jesus fired the rebound over. De Sanctis got down low to turn Alvaro Pereira's grasscutter around the post.
Cavani saw an effort whistle past the post, before Marek Hamsik just missed sliding in to get on the end of a low cross from the forward, who was all over the pitch.
Inter were given a way back into the match halfway through the first half. Juan Zuniga pushed Alvarez over in the box and the referee awarded a penalty. Ricky stepped up himself, De Sanctis got a touch, but he couldn't keep the spot kick out. The Nerazzurri were level, but were immediately put onto the backfoot once again.
Handanovic stopped a Blerim Dzemaili screamer, before Zuniga redeemed himself for the earlier penalty by winning one himself. A clumsy challenge by Jonathan was penalised and Handanovic hardly moved as Cavani stepped up to blast his 100th strike into the corner.
Napoli looked to put the game to bed after the restart. Pandev collected a Hamsik pass and opted to shoot rather than play the one-two and Handanovic smothered the shot. Hamsik then saw a shot blocked in the box with Christian Maggio lurking at the far post.
Alvarez stung De Sanctis' palms, then Ranocchia pulled Cavani down in the area, but play was called back for an earlier Juan Jesus foul on Pandev. Inter were given a reprieve, yet continued to ride their luck. Pablo Armero came on and instantly crossed for Cavani to glance wide from six yards.
Napoli finally made Inter pay 12 minutes from the end. Cavani passed to Pandev and the Macedonian's ball across the box was swept in by the Uruguayan, who had sprinted past the lapsadaisical Nerazzurri defence en route to settling the game and taking home the match ball.
Napoli: De Sanctis; Gamberini, (Rolando 62) Cannavaro, Britos; Maggio, Behrami, Dzemaili, (Armero 66) Zuniga; Hamsik; Pandev, (Insigne 85) Cavani
Inter Milan: Handanovic; Ranocchia, (Schelotto 83) Chivu, Juan Jesus; Jonathan, Kuzmanovic, (Pasa 83) Kovacic, Benassi, (Cambiasso 46) Pereira; Guarin, Alvarez
Goals: Cavani 3, pen 33, 78 (N) Alvarez pen 23 (I)