Jose Mourinho's dislike of Arsenal manager Arsene Wenger has been well documented, and there are now claims the former Chelsea boss even threatened to hit the Frenchman at one point.
The intense rivalry has seen the bosses aim many a verbal volley at each other in the press, and in 2014, during a game between Chelsea and Arsenal, the pair even got into a shoving match.
According to a book by journalist Rob Beasley, Jose Mourinho: Up Close and Personal, there was one incident that really got Mourinho worked up: when Wenger spoke of how Arsenal could be hurt by Mancheste United because of Chelsea's decision to sell Juan Mata to in 2014.
A few days after the Frenchman's comments, the Portuguese tactician was quoted by Beasley as saying he would punch Wenger if he saw him away from a football ground.
"When Mr Wenger criticises CFC and Man United over the deal with Mata... I will find him one day outside a football pitch and I will break his face," Mourinho is alleged to have said, according to an excerpt from Beasley's book.
Chelsea went on to beat Arsenal 6-0 later that week, in Wenger's 1 000th game in charge of the Gunners.
Do you think there will be fireworks when Wenger and Mourinho meet on the touchline this season? Have your say in the comments section below.