That was in vain as Koulibaly shinned a deep free-kick past his own keeper.
Juve, who have won the last eight titles, clearly lacked the presence of captain Giorgio Chiellini – likely to be out for several months with an anterior cruciate ligament injury – at the back, with £67.5m summer signing Matthijs de Ligt making a shaky debut.
How Juventus took control
The contest looked over after 62 minutes, with Juventus very impressive in the first half especially.
Former Manchester City defender Danilo had to come on to replace the injured Mattia de Sciglio, and 29 seconds into his debut he scored after converting Costa’s cross to finish off a swift counter-attack.
Higuain then doubled the lead brilliantly as he turned Koulibaly before smashing the bouncing ball past Alex Meret with the outside of his foot. Ronaldo added a third in the second half as he finished another Costa cross.
The Napoli comeback
Former Roma defender Manolas’ header from Mario Rui’s cross in the 66th minute looked a mere consolation.
But two minutes later they had real hope when Lozano, on his debut following a move from PSV Eindhoven, slotted in from Mario Rui’s cross to become the first Mexican to ever score in Serie A.
Juventus winger Costa had a good shot tipped on to the woodwork by Meret – and that save looked crucial moments later.
The dream looked set to become a reality for Napoli, who have finished second to Juventus in three of the past four seasons, when Di Lorenzo, a summer signing from Empoli, beat De Ligt to the ball to scramble home a free-kick.
There was one more Napoli goalscorer, but sadly it was into his own net as Koulibaly, scorer of a famous winner against Juve in April 2018, got his angles wrong and rifled Paulo Dybala’s deep free-kick past Meret.
- 2De SciglioSubstituted forDaniloat 15′minutes
- 4de Ligt
- 12Lobo SilvaBooked at 80mins
- 6KhediraSubstituted forCanat 60′minutes
- 14MatuidiBooked at 52mins
- 11Douglas CostaBooked at 83mins
- 21HiguaínSubstituted forDybalaat 76′minutes
- 7Cristiano Ronaldo
- 16Ju Cuadrado
- 22Di LorenzoBooked at 44mins
- 31GhoulamBooked at 40minsSubstituted forMário Ruiat 45′minutes
- 5Marques LoureiroSubstituted forElmasat 74′minutesBooked at 90mins
- 24InsigneSubstituted forLozanoat 45′minutes
- 6Mário Rui
- Daniele Orsato
- Shots on Target
Hand ball by Miralem Pjanic (Juventus).
Attempt missed. Douglas Costa (Juventus) left footed shot from the right side of the box is too high.
Miralem Pjanic (Juventus) wins a free kick on the left wing.
Foul by Emre Can (Juventus).
Douglas Costa (Juventus) is shown the yellow card for a bad foul.
Foul by Douglas Costa (Juventus).
Alex Sandro (Juventus) is shown the yellow card for a bad foul.
Foul by Alex Sandro (Juventus).
Delay over. They are ready to continue.
Delay in match because of an injury Matthijs de Ligt (Juventus).
Attempt missed. Matthijs de Ligt (Juventus) right footed shot from outside the box is too high. Assisted by Blaise Matuidi.
Emre Can (Juventus) wins a free kick on the right wing.
Attempt saved. Douglas Costa (Juventus) left footed shot from outside the box is saved in the top right corner. Assisted by Emre Can.
Foul by Leonardo Bonucci (Juventus).
Foul by Blaise Matuidi (Juventus).