Juventus' record-breaking 43-match undefeated run came to an end when Napoli won the Italian Cup 2-0.
Serie A champions Juventus saw their hopes of a league and cup double shattered by two second-half goals, with defeat particularly painful for skipper Alessandro Del Piero, who was playing the last match of his 19-year career with the club.
Uruguayan striker Edinson Cavani opened the scoring from the penalty spot in the 62nd minute when goalkeeper Marco Storari brought down Ezequiel Lavezzi.
It was Cavani's 33rd goal of the season.
Seven minutes from time, Napoli's first Italian Cup triumph since Diego Maradona's team won the 1987 double was assured when Goran Pandev launched a lightning counter-attack before playing in Marek Hamsik, who slotted the ball into the corner.
Juventus striker Fabio Quagliarella was sent off in the last minute for elbowing Salvatore Aronica in the face.
"It's almost unthinkable to beat Juventus over 90 minutes when they hadn't lost all season. It was an achievement within an achievement," said Napoli coach Walter Mazzarri.
In a tight first-half at the Olympic Stadium, Juve believed they should have been awarded a penalty when Claudio Marchisio was clipped by Aronica as he was about to shoot.
Chances remained few and far between until the 63rd minute when Napoli were awarded a penalty after Lavezzi had nipped between Leonardo Bonucci and Andrea Barzagli and Storari brought him down.
Del Piero was substituted shortly after, bringing an end to a career which had featured 705 matches and 289 goals.
Napoli keeper Morgan de Sanctis saved a Leonardo Bonucci volley at the base of the near post while an Andrea Pirlo free-kick came off the defensive wall as Juve pushed for an equaliser.
Napoli then seized their chance to bury the game when Juventus were caught cold on the counter and Hamsik coolly shot across Storari and into the far corner.
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