Paolo Di Canio has hit back at Martin O'Neill as the war of words between the former Sunderland managers continued.
Di Canio succeeded O'Neill at the Stadium of Light in March and, on his arrival, criticised the fitness levels in the squad.
O'Neill took his time to respond but following his appointment as Republic of Ireland boss earlier this week, he dismissed Di Canio's barbs and labelled the Italian a "managerial charlatan".
Di Canio, who led Sunderland to Barclays Premier League survival last season before being sacked after five games of the current campaign, told Sky Sports News on Friday: "I don't know if he knows the meaning of this word charlatan. Probably I can teach him, even if I am not English.
"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 £40m to be a top 10 club and then sees the club sink into the relegation zone."
Di Canio stood by his claim that the Black Cats players were not in peak condition when he arrived on Wearside.
"The fitness levels were pathetic," he said.
"I had players who told me they had cramps from driving the car.
"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."
Di Canio was dismissed after a 3-0 defeat at West Brom, a result which was reportedly followed a day later by a training ground bust-up with senior players which led them to ask the board to take action.
Di Canio insisted, however, that no argument took place.
"It never happened," he said.
"There was a typical meeting, as there was after every game to see the clips and analyse the game.
"Maybe there was opinion but this happens in every good family."
Even though his first foray into top-flight management ended in acrimonious fashion, it has not quelled Di Canio's confidence and he remains hopeful of finding another job in England.
"I was too good, my level was too high," he said of his experience at Sunderland.
"What doesn't kill me makes me stronger. I can't wait to have another chance with the right people. I feel a better manager than before.
"Even if I have requests from around Europe I say no.
"There is no space for me in England at the moment but I will wait.
"It would be stupid for a chairman not to call me. Even if it's at a Championship club with a project."