Napoli roared back from 3-0 down against Juventus only for Kalidou Koulibaly's injury-time own goal to hand the Serie A champion a dramatic 4-3 victory on Saturday.
Juve, whose coach Maurizio Sarri was again absent from the Allianz Stadium due to a bout of pneumonia, produced a commanding performance for the first hour to open up a sizeable lead over Carlo Ancelotti's side.
Danilo broke the deadlock with his first touch just 29 seconds into his debut as a substitute for Mattia De Sciglio, before Gonzalo Higuain doubled the lead against his old club and Cristiano Ronaldo struck a third.
Napoli was allowed back into the match through quick-fire goals from Kostas Manolas and Hirving Lozano, another man in his first Serie A outing, before Giovanni Di Lorenzo thought he had earned a dramatic draw.
However, in the second minute of injury time, Koulibaly put through his own net to gift Juve an early boost in the Scudetto race.
Wojciech Szczesny saved superbly from Allan and Juve struck within seconds of the resulting corner being cleared, as Douglas Costa raced into the box and pulled the ball back for Danilo to finish.
It was 2-0 three minutes later, Higuain spinning away from Koulibaly and firing into the top-right corner in fine style.
Victory for a commanding Juve was seemingly assured 62 minutes in, when Ronaldo met Costa's cut-back and placed a left-foot shot beyond the attempted block of Koulibaly and dive of Alex Meret for his first goal of the season.
Suddenly, though, they seemed to crumble. Manolas met Mario Rui's cross with a fine header and, barely two minutes later, Lozano slotted past Szczesny after being picked out by Piotr Zielinski from the left.
Costa's shot was brilliantly tipped onto the bar by Meret and, as anxiety seemed to build within the stands, Napoli snatched an equaliser when Di Lorenzo diverted Jose Callejon's delivery into the net from inside the six-yard box.
Yet with barely 90 seconds remaining, a hopeful free-kick was lofted into the Napoli area and Koulibaly sliced a clearance high into his own net with no Juve player nearby.
What does it mean? Juve's collapse offers hope to chasing pack
Many had predicted Napoli to provide a far greater threat in the title race this season and it looked a long way below the standards of the Old Lady for the first hour here.
That said, the way Juve gave up its lead will be of huge concern to Sarri. The manner in which it went from authority to calamity in the second half was alarming, and only Koulibaly's awful miscue denied Napoli a draw it barely deserved until those breathless final 25 minutes.
Crafty Costa offers something different
Juve is blessed with huge depth in attack but few of its forwards offer the same direct threat as Costa does on this kind of form.
The Brazilian got two assists and smashed the crossbar with a fierce strike. He at least deserved to win.
De Ligt does not deliver
Serie A debutant De Ligt lost Manolas for Napoli's first goal, was well out of position for the second and let Di Lorenzo score the third. With Giorgio Chiellini sidelined for the foreseeable future, he will need to sharpen up quickly.
Key Opta Facts
The last Serie A encounter between Juventus and Napoli with seven or more goals was back in March 1993.
Danilo found the net 29 seconds after joining the game: the last player to have scored a faster goal in his Serie A debut with a new club was Duvan Zapata for Sampdoria in September 2017 (17 seconds).
Danilo is the first Juventus player to find the back of the net on his debut in Serie A since Miralem Pjanic (10/9/2016 vs Sassuolo).
The last Napoli player to score an own goal vs Juventus was Ciro Ferrara in December 1993.
Napoli has conceded seven goals in the first two matchdays in Serie A. It last conceded more (eight goals) over the first two matchdays back in 1962-63.
Juventus heads to Fiorentina after the international break, while Napoli hosts Sampdoria.
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