Milan - Gonzalo Higuain "betrayed" Napoli by joining rivals Juventus, claimed club owner Aurelio De Laurentiis despite pocketing 90m euros ($98.8m, 75.3m) for the sale of the Argentine striker.
In the most unlikely move of the Serie A summer transfer period, Higuain ended his fairytale three-year spell with Napoli on Tuesday when he agreed to a record five-year deal with the Italian champions that is expected to earn him €7.5m euros a year.
As Juventus fans mostly rejoiced, their Napoli counterparts reacted by posting photos of their idol's Napoli shirt in the toilet.
And De Laurentiis, despite a bulging bank account, was not far behind in slamming the 28-year-old striker whose record tally of 36 goals last season took Napoli to the brink of ending their 26-year wait for the Serie A title.
He told Corriere dello Sport: "Some people say that to speak of betrayal is exaggerated, but I think the opposite because there is the full sense of betrayal in this (Higuain) choice because of the ingratitude shown.
"Obviously I have to consider the role played by Juventus, but I expected a different kind of behaviour (from Higuain)."
Higuain was feted as the King of Napoli only two months ago when he broke Gunnar Nordahl's 66-year-old record of 35 goals in a single Serie A season as the Azzurri battled Juve for a 'scudetto' title they last won in 1990.
In the end, Napoli finished second but Higuain was undoubtedly the star of last year's campaign.
De Laurentiis slapped a 94.7m euros buyout clause into his contract but when Juventus offered 90m euros over two instalments, the Napoli owner buckled.
De Laurentiis conceded the transaction was above board. But he said Higuain's snap decision to quit Napoli, following advice from his brother and agent, reflected the "unscrupulous" nature of the modern game.
"True, there was the clause so there was no formal impropriety... but the unscrupulous nature of football means there is no respect for sentiment," added De Laurentiis.
"We understood, as soon as Higuain's brother spoke, that we might run the risk of having to look for a new centre-forward.
"But we didn't think that risk was serious, or that he (Higuain) could simply wipe clean his three years spent with Napoli."
Higuain was undergoing a medical in Turin on Wednesday morning ahead of signing a five-year deal that will make him the third most expensive signing in history after Gareth Bale and Cristiano Ronaldo.
He will be officially unveiled on Thursday.
But Higuain's shock move to what remains the most potent, revered and hated club in Italy was met with mixed reaction.
For Italian icon and one-club man Francesco Totti, who is set to play his final season with Roma, it is a disaster that smacks more of "business than passion".
"Look at what's happened now with Gonzalo Higuain leaving Napoli for Juventus. It's a disaster," said Totti.
"But, it's completely normal now that when a foreigner comes to Italy he has the possibility of going to another team to make more money."
Napoli already had their sights set on Inter Milan striker Mauro Icardi, although Polish international Arkadiusz Milik (Ajax) is tipped as a more realistic replacement for Higuain.