It's fair to say Jose Mourinho and Arsene Wenger haven't always seen eye-to-eye throughout their career.
The pair came to blows at Stamford Bridge two years ago during Chelsea 2-0 victory over Arsenal but their war of words stems back a lot further than that.
And the two managers will clash once again in the Saturday lunch-time kick-off as Arsenal travel to Old Trafford to face Manchester United in what is sure to be a pulsating affair.
In 2005, Wenger blasted Mourinho in a rant branding him 'disrespectful' and 'stupid' after the Portuguese boss claimed the Frenchman had an obsession with Chelsea.
Wenger said: “He's out of order, disconnected with realistic and disrespectful. When you give success to stupid people, it makes them more stupid sometimes and not more intelligent."
Nine years later, in February 2014, Mourinho called the Arsenal manager a "specialist in failure" after he had gone several years without a trophy.
Just two examples of the duo bad-mouthing each other in the media.
And one of them was always going to make a comment ahead of the big match this weekend, weren't they?
That man was Mourinho who seemingly mocked Wenger for his lack of a league title in recent years.
The 'Special One' claimed that journalists respected his counterpart more than him, despite his recent Premier League record.
"Mr Wenger has that respect from all of you. I don't think I have it," he claimed
"My last league title was 18 months ago, not 18 years ago."
Of course, Mourinho is fully aware that Arsenal's last league success was 12 years ago, rather than 18 years ago, but he was just emphasising his recent Premier League success compared to Wenger's.
It's understandable that Mourinho is maybe feeling a bit of pressure on his shoulders ahead of the match. United are already eight points off league leaders Liverpool and know they must beat Arsenal to haul themselves back into a title race.
As for Wenger, his Arsenal side are in a fantastic position to end their long top-flight drought.
The Gunners are unbeaten in 10 league matches and are six points ahead of the Red Devils in fourth. A win against their rivals on Saturday will certainly silence Mourinho but Wenger will need to end his Premier League drought if he is to shut him up for good.