Napoli saw their 100 percent start to the Serie A season ended as they were held to a 0-0 draw by second-placed Inter Milan at the Stadio San Paolo.
Dries Mertens missed two fine chances to extent the hosts' winning run to nine games, but ultimately a strong defensive display from the visitors earned a deserved point.
The confident home side looked eager to prove their superiority from the start against opponents who had signalled their own intentions with a thrilling derby win last week.
Marek Hamsik stretched the visiting defence in the early stages and had the first chance of the game when he drilled a fifth-minute effort just wide of Samir Handanovic's post.
Lorenzo Insigne was also a threat for the hosts in the early stages but Inter held firm and broke well, Ivan Perisic sending a dangerous ball across the Napoli box.
Handanovic produced a superb double save in the 19th minute, first blocking a shot from Jose Callejon then getting back down to prevent Mertens slamming home the rebound.
Mertens should have done better with the finish and Napoli were almost made to pay six minutes later when Perisic met an Antonio Candreva cross with a firm header that flew inches over the bar.
Kalidou Koulibaly shot over from a tight angle for Napoli but it was Inter who ended the first half on top with Borja Valero forcing a fine fingertip save from Jose Reina.
The visitors threatened again shortly after the restart when Matias Vecino rounded Reina and fired goalwards from an acute angle, only for Raul Albiol to save his side by heading off the line.
Inter's rearguard was looking increasingly confident but Napoli were not without their chances, with Insigne hitting another effort just wide with Handanovic beaten.
Nerazzurri substitute Joao Mario had their last chance to win it in the 77th minute when he found space to fire across Reina's goal, although the keeper appeared to have it covered.
Napoli finished well, with substitute Piotr Zielinski hitting a powerful drive which was blocked in the box before Mertens stretched for one final attempt which was tipped around the post by Handanovic.