Napoli face a play-off to qualify for the Champions League after a 4-2 win at Sampdoria on a dramatic final day of the Serie A season was not enough to snatch second place from Roma.
Dries Mertens, Lorenzo Insigne, Marek Hamsik and Jose Callejon all scored as Napoli finished the campaign strongly, winning 11 of their last 13 away games to end with a club-record 86 points.
But, after Diego Perotti struck a late winner for Roma in a 3-2 win against Genoa in Francesco Totti's farewell, Maurizio Sarri's men had to settle for third place in the final table.
Napoli started brightly with Mertens and Insigne forcing saves from Christian Puggioni before Callejon failed to apply the finishing touch as Insigne flashed a centre across the Sampdoria box.
But the breakthrough finally arrived in the 36th minute, Mertens marking his new long-term contract at the club with a spectacular long-range strike.
Sampdoria captain Vasco Regini miscued a clearance to the Belgian and, with Puggioni out of position, Mertens lifted home a beautiful finish from 25 yards for his 28th league goal of the season.
And Napoli doubled their lead with another beautiful goal before half-time, Insigne racing clear down the left and bending a sensational shot across Puggioni and into his top-left corner.
Napoli's dominance continued after the interval as Marek Hamsik headed home from close range after Callejon nodded a Mertens cross back for the captain to provide a simple finish.
But Sampdoria replied immediately, veteran forward Fabio Quagliarella turning home Patrick Schick's flicked header against his old club.
That lapse was soon forgotten as Napoli scored the best goal of the game, Callejon superbly volleying Insigne's cross beyond Puggioni for the team's 94th Serie A goal of the season.
In the last minute of normal time substitute Ricardo Alvarez squeezed home a second for Sampdoria, but more importantly, Perotti rifled home at the Stadio Olimpico to render Napoli's win irrelevant.