Antonio Conte apologised to Napoli fans after Sunday's 3-0 humiliation at Verona in his first Serie A match in charge, while last season's surprise package Bologna were held to a 1-1 draw by Udinese.
Verona new boys Dailon Livramento and Daniel Mosquera, with a brace, were on target in the second half at the Stadio Marcantonio Bentegodi, giving Conte a nightmare league start at troubled Napoli.
"We have to say sorry to our supporters because it was a second half that was, well it's difficult even to assess what happened," said a baffled Conte to DAZN.
"In the first half there was only one team on the pitch and it was Napoli. Then we came out for the second half maybe too satisfied with ourselves for the first half performance even though we were still goalless. But it wasn't the same attitude as in the first half."
Conte blasted his team, who only scraped past Serie B outfit Modena on penalties in the Italian Cup last weekend, for melting "like snow" once Livramento put Verona ahead four minutes after half-time.
"It is really worrying. Good teams react to difficult situations... but we completely fell apart," added Conte.
"I'm the coach and it's my responsiblity, so I apologise. It was a debacle and it's my fault."
On Saturday Conte described this season as "year zero" after Napoli finished 10th as defending champions in their previous disastrous campaign in which they went through three different coaches.
The former Juventus, Chelsea and Italy coach also warned against heightened expectations from fans as he waits on reinforcements while Victor Osimhen, the star of Napoli's historic 2023 title triumph, has been frozen out for pushing for a transfer.
And although Napoli were comfortably the better team in the first half the loss of talisman Khvicha Kvaratskhelia to injury just before the break proved crucial.
Kvaratskhelia was hurt by Pawel Dawidowicz after a last-ditch Jackson Tchatchoua tackle denied the Georgian star a chance to open the scoring.
With Kvaratskhelia off Napoli had much less cutting edge and Verona took the lead when Livramento neatly guided home Darko Lazovic's pinpoint cross.
Substitute Mosquera secured the points with a debut goal of his own 15 minutes later after chaos in midfield ended with the Colombian bursting through and confidently rolling home past Alex Meret.
And Mosquera made the scoreline even more embarrassing for Napoli and Conte in stoppage time when left all alone to tap in Lazovic's low pass.
"It's crazy, we drive every day to training together, we're both strikers but we're good teammates on and off the field," said Cape Verde forward Livramento of his friendship with Mosquera.
Bologna were also playing their first match under a new coach in Vincenzo Italiano, who was denied a win by Lautaro Giannetti's 68th-minute header for Udinese.
Argentine Giannetti struck seconds after Bologna goalkeeper Lukasz Skorupski saved Florian Thauvin's penalty, denying Bologna who deservedly took the lead in the 57th minute through a Riccardo Orsolini spot-kick.
Although the draw is a disappointing result Bologna played with the same verve as they did last season when under Thiago Motta they qualified for the modern Champions League for the first time in their history.
They did so without last season's departed stars Joshua Zirkzee and Riccardo Calafiori while Lewis Ferguson's knee injury will keep him out for months.
Lazio got their campaign under way by coming from behind to beat promoted Venezia 3-1 while their capital city rivals Roma were held to a goalless draw at Cagliari.
