In 2007 Arsene Wenger referred to Jose Mourinho as "a chequebook manager" - with the Portuguese boss firing back and branding the Frenchman "a specialist in failure" seven years later.
Fast forward another five years and two of the best managers in football history will share the same studio when they provide punditry on this year's Champions League final in Madrid.
The pair have been regular contributors to beIN Sports' Champions League coverage this season but never crossed paths on air. Until now.
It's been confirmed that, in a world first, the two rivals will team up to analyse the all-English clash between Spurs and Liverpool at the Wanda Metropolitano.
With two of the very best football minds in the business teaming up, those watching on beIN Sports are sure to be in for a treat.
It would be fair to say that Wenger and Mourinho haven't always seen eye-to-eye over the years - even getting physical on the touchline - but there is respect there between them.
In fact, when Wenger announced he was leaving Arsenal after 22 years, Mourinho was full of praise for his opposite number.
"If he's happy I'm happy, if he's sad, I'm sad," Mourinho told the media at his news conference.
"I always wish the best for my opponents. You don't know the way we respect each other even when sometimes it doesn't look like we don't.
"Players that get yellow cards and red cards by aggressive actions against each other - the manager is the same thing but the ones that respect more each other are the ones with the problems.
"It's power and ambition and quality against each other but in the end it's people from the same business and we respect each others' career."