In 2004, Arsenal did what no team before them, or after them for that matter, have ever done in the Premier League.
The Gunners completed an entire domestic league season undefeated and that team has since become known as The Invincibles.
That famous squad oozed class and included the likes of Freddie Ljungberg, Robert Pires, Dennis Bergkamp and of course, Thierry Henry and Patrick Vieira.
Although every member of the team played an important role in helping the Gunners go undefeated, arguably, Vieira and Henry were two of the standout players.
The pair spent six years of their club careers together and also won a World Cup and European Championship in the same France team, so it's fair to say that they know each other very well.
But more recently, they've become rivals.
That's because both men now manage clubs in Ligue 1, with Henry at Monaco and Vieira at Nice.
And on Wednesday night, their two sides met for the first time this season - which put the old teammates in opposite dugouts for the first time.
The game itself ended 1-1 at Monaco's Stade Louis II, with the visitors taking an early lead.
However, a red card saw Nice down to 10 men and the hosts made their numerical advantage count, equalising in the second-half.
With the points shared, some of the attention turned back to the two bosses, and after the game, Henry was asked about what it was like to take on his old teammate as a manager.
"Weird, really weird. When I saw him coming out of the locker room, it felt weird," he replied, per the Daily Mail.
"We walked the steps together, we used to climb them together when we played. It was really good, [we shared] a wink. But then there's the game and you do what you have to do.
"He did what he had to do, but it felt weird. We talked, we said a few things to each other."
WHAT THE PAIR TALKED ABOUT
Although Henry remained tight-lipped about what the pair discussed, Vieira was more than happy to reveal what they said during a warm embrace before kickoff.
"We both just wished each other luck, that's all."
With the two Arsenal legends now managing in the same league, this won't be the last time they're in opposite corners - and every time they meet, it will be interesting to see who comes out on top.