Newly appointed Republic of Ireland boss O'Neill criticised the Italian for blaming his methods at the club, such as fitness training, and the ex-Swindon Town boss has promptly responded in a predictably volatile manner.
"It was like a 27-year-old manager stepping in and the first thing you do is criticise the fitness of the team," O'Neill said. “If you've ever seen [my old side] Aston Villa play, you'll see the one thing I pride myself on is teams being fit. What's interesting is that, when he started, the team supposedly wasn't fit for the Chelsea game. Then, the following week when he won at Newcastle, not being fit wasn't mentioned.
"Then about two weeks later they got mauled by Aston Villa and someone asked him about the fitness. Suddenly, he didn't know where to go because the team, as it progresses, should be getting more fit."
Di Canio, who was replaced by Gus Poyet last month, hit back in the war of words, stating that O'Neill didn't know the meaning of “charlatan”, after the former Celtic boss had hurled that particular insult in Di Canio's direction.
"I don't know if he knows the meaning of this word, 'charlatan'. Probably I can teach him, even if I am not English," Di Canio told Sky Sports News.
"I respect the opinion of manager Martin O'Neill but the fact that he spoke after six months, not straight away - that proves what kind of level he is. He is not very big. A charlatan is a manager who spends £40 million to be a top-10 club and then sees the club sink into the relegation zone."
Ultimately, this squabble between failed ex-Sunderland bosses is slightly embarrassing, but Di Canio does fail to point out that he did spend over £20m on summer signings including Emmanuele Giaccherini and Jozy Altidore, and whilst they lost Simon Mignolet to Liverpool, Di Canio was handsomely backed in the transfer market and failed to take advantage – which he should be held accountable for.
image: © Hilton Teper