(REUTERS) - Former Sunderland manager Paolo di Canio hit back at Martin O'Neill's criticism of his time at the English Premier League football club by saying the new Ireland manager was "not very big".
Ulsterman O'Neill, who was sacked by Sunderland in March as they faced the prospect of relegation and replaced by di Canio, called the Italian a "managerial charlatan" last week.
"I don't know if he knows the meaning of this word 'charlatan'," di Canio said in an interview with Sky Sports News broadcast on Friday. "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 40 million pounds (S$80 million) to be a top-10 club and then sees the club sink into the relegation zone," the 45-year-old added.
Di Canio, who had previously coached third-tier Swindon Town, publicly questioned the fitness of the Sunderland players when he took over from O'Neill and reiterated his belief that it had been poor.
"The fitness level wasn't bad, it was pathetic," the former striker said.
"I had players who told me they had cramps from driving the car," he said. "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 kept Sunderland in the Premier League last season but was sacked five games into the current campaign following a 0-3 loss at West Bromwich Albion which left the club bottom of the table on one point.
The British media reported a training ground bust-up the day after the defeat led to the squad demanding that club owner Ellis Short remove di Canio, but the Italian denied this had happened.
"It never happened. There was a typical meeting that I used to have the day after every game to see the clips, to analyse the game. Maybe there was opinion but this happens in every good family," he said.
Despite his first managerial post at a Premier League club ending in acrimonious circumstances, di Canio, who enjoyed a colourful playing career with clubs including Juventus, Milan, Lazio, West Ham and Celtic, was confident of working in England again.
"What doesn't kill me makes me stronger. I can't wait to have another chance with the right people that let me work in my way," he said. "Now I feel a better manager than before, much better.
"Even if I have requests from around Europe I don't go. I understand that in England there is not any more space for me so I'll wait.
"It would be stupid for some chairman if they don't call me. Even if it's at a Championship (second-tier) club with a project."