The new Republic of Ireland manager was unhappy with Di Canio's conduct after the Italian replaced him at the Stadium of Light in March and his stinging criticism has prompted a furious response from the 45-year-old, who questioned the former's grasp of the English language.
"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.
|8/11||Sunderland are 8/11 with Bet365 to avoid relegation from the Premier League|
"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."
Di Canio also stood by his previous criticism of player fitness when he arrived at Sunderland, while accusing Phil Bardsley of "treason" after he mocked the club's 1-0 opening-day loss to Fulham via social media.
"I had players who told me they had cramps from driving the car," the ex-Swindon Town boss added. "I had three players with injuries in the calf after 20 minutes of a game. Six different players with problems means they were not fit.
"At the beginning of the season, [Bardsley] made tweets celebrating the defeat of the club that pay him. A person at the club came to me and said: 'We want to fine him', and I agreed.
"He was celebrating; that is the worst treason for the people next to you. It is clear that he tried to destroy his career on his own."