Antonio Conte has slammed "little man" Jose Mourinho for digging up old match-fixing charges against the Chelsea manager in recent press statements.
The pair have maintained a frosty relationship since Conte arrived in the Premier League, with frequent clashes when the Blues have faced Manchester United.
But Mourinho upped the ante in their war of words by referencing a four-month ban Conte served in the 2012-13 season while he was manager of Juventus for failing to report match-fixing while he was in charge of Siena.
"What never happened to me and will never happen is to be suspended for match-fixing," he told reporters on Friday - words that brought furious reaction from his rival.
Conte, not to be outdone, came back with his own strong words toward the Manchester United boss, calling him "a fake" and claiming that he will always be a "little man".
"You show you are a little man," Conte said after a weakened Chelsea side were held 0-0 by Norwich City in Saturday's FA Cup third round.
"He was a little man in the past, he is a little man in the present and he will be in the future.
"He is not my problem, I consider him a very little man with very low profile. I remember for example with Ranieri.
"He offended Ranieri for his English, then when Ranieri was sacked he put a shirt with his name on. This shows you are a fake."
Conte hit out at his United counterpart further, claiming his grasp of the situation which led to his suspension is not clear.
"Before [making these comments] you have to know the truth very well," he added. "The truth is that I was banned for four months for failure to report [match-fixing]. Then I requested a real trial through the court and they declared my innocence.
"I think before you make this type of comment, to hurt another person, you must pay great attention.
"You know him very well. The level is very low. I repeat: I think before to speak you have to know very well what happened."
When asked if he would like clarity from the Portuguese, the Italian made it clear that he doesn't think Mourinho will be ready to face up to him when their two sides meet next month.
"There will be an opportunity for answers at Old Trafford when I see him face to face. I will be ready, I don't think he is ready."
Manchester United and Chelsea will lock horns in the Premier League on February 25, with the Theatre of Dreams playing host to that long-awaited bout.