For 22 years, Arsene Wenger was one of the Premier League's key figures, presiding over an Arsenal side that he led to three Premier League titles and seven FA Cups.
The rivalry with Alex Ferguson's Manchester United was a defining part of that period in charge and their tussles often decided the destination of the major trophies in Wenger's first decade in North London.
While he had Patrick Vieira in his own ranks as an on-pitch lieutenant, Roy Keane fulfilled a similar role for Man United and almost two decades on from the height of the rivalry, Wenger retains admiration for the former Republic of Ireland captain as he told this week's Late Late Show.
"First of all, Roy Keane was an exceptional football player. After that, he was as well a leader," said the Frenchman, who is now Chief of Global Football Development at FIFA two years on from his Emirates Stadium departure.
"You could feel who was the leader there [at Man United] and it was him. And you could even feel that some players inside his own camp were scared of him.
"But he was a highly motivated player and I believe he contributed hugely to the success of Ferguson because this kind of player keeps the dressing room on their toes, so he was an exceptional football player."
While Keane kept United colleagues on their toes, it was arguably Wenger's greatest ever player Thierry Henry whose hand infamously dealt a blow to Ireland's hopes of qualifying for the 2010 World Cup as he set up William Gallas' goal.
Reflecting on that November 2009 episode and its aftermath, Wenger said: "I felt that Thierry Henry had the reflex of a goalscorer like Maradona had against England when he scored with a handball.
"After that, it was more embarrassing because I believe it was a tough time for Thierry because the federation didn't help him. I think the French Federation should have offered to replay the game and Thierry Henry was very lonely after.
"But it tells you one thing, today that sort of situation couldn't happen anymore because we have a VAR and the goal would be cancelled. That shows you there are some good arguments for the VAR."
Wenger also spoke of the regrets from his time as a manager.
"I have regrets because when you look at your life, if happiness is to lead the life you want, I can say I'm very happy," he said.
"If I judge my behaviour towards all my family, I would say 'selfish.'"
Watch the full interview on the RTÉ Player.