Allegedly, Jose Mourinho said he would break Arsene Wenger's face in the past - something a journalist put to him at a press conference before Saturday's game against Chelsea.
The alleged threat is quoted in a new book about the Manchester United manager entitled Jose Mourinho Up Close and Personal. According to the book Mourinho made the threat whilst at Chelsea, saying if Wenger meddles in the club's business he would "break his face".
Wenger said he did not want to comment on the matter and that he had no intention of reading the book.
"I comment on football, that's all I do," said Wenger. "I'm not in a destructive mode. Never. I am more constructive."
On Saturday's game, the Arsenal manager called for his defence to be "completely cold-blooded" and keep their discipline, and could negate Diego Costa by staying focused and not be tempted into a battle with the Spanish forward.
Last season, Arsenal ended the game with nine men as they lost 2-0 at Stamford Bridge - to a Chelsea side managed by Mourinho.