Napoli's torrid start to the season continued Saturday when Venezia head coach Davide Nicola masterminded a shock 1-0 win on debut as Kevin De Bruyne had a penalty saved.
Renowned survival specialist Nicola was appointed during the week to replace sacked coach Giovanni Stroppa after last season's Serie B champions failed to pick up a single point in their opening six games.
He made an instant impact as Akor Adams struck the winner early in the second half to seal Venezia's first Serie A win over Napoli since 1942.
It marked a second defeat in a row for Massimiliano Allegri's side after their midweek Champions League loss at Villarreal, and the first time in 25 years that Napoli have lost five of their first nine games in all competitions.
"In football you get moments like this and there is only one way out: keep working seriously and professionally, be more focused and turn this disappointment into anger," Allegri told a press conference before ahead to Tuesday's home game against Bodo/Glimt.
"It's up to us to turn this situation around, starting with the Champions League."
A flat game came to life early in the second half when Nigeria international Adams latched on to a long ball and beat Alex Meret with a deflected strike in the 49th minute.
Allegri responded by bringing on rested stars Rasmus Hojlund and Kevin De Bruyne and the Danish striker immediately threatened when Juan Jesus denied him a tap-in with a superb goal-line block.
Hojlund won a penalty for Napoli midway through the second half when he was hauled down in the box by Matias Moreno, but De Bruyne's spot-kick was well saved by Filip Stankovic low to his right.
The Venezia goalkeeper, son of former Inter midfielder Dejan Stankovic, was decisive in the closing stages with a string of saves, including spectacular stops to deny Stanislav Lobotka and Alisson Santos.
Napoli are ninth after picking up 10 points from their first seven games, while Venezia remain bottom with three points.
Later on Saturday, league leaders Inter travel to Bologna before Roma host Genoa.