It started, as feuds often do, with a misunderstanding. At least that is Watford boss Walter Mazzarri's explanation for why we might expect a frosty air to the greetings when he and Chelsea's Antonio Conte meet for the first time as Premier League managers at Vicarage Road on Saturday.
In 2012, the previously cordial relationship between the men then in charge of Juventus and Napoli, Serie A's two ascendant powers and traditionally bitter rivals, turned on a comment made by Mazzarri.
"There was a certain point when I said that, when they faced us, [Conte] changed the style of play that he believes in, convinced I was paying him a compliment," Mazzarri explained in his autobiography.