Despite beating Genk 4-0 to secure knockout Champions League football, Napoli dismissed coach Carlo Ancelotti on Tuesday night.
Aurelio de Laurentiis and his directors made the decision, which was shared on social media after the final whistle.
Before the game took place, Ancelotti had cast doubt over his own future as results in Serie A continue to disappoint.
"I've never resigned and I don't think I will, tomorrow I will meet with De Laurentiis to take a decision," he had said.
The falling out with De Laurentiis is also reported to be linked to Ancelotti's reluctance to extend his contract when the club's president wanted him to do so.