Arsene Wenger and Sir Alex Ferguson's relationship was once frosty, verging on vehement.
Now the two have cooled considerably and could even be described as old chums.
This article will look back through the history of their rivalry and pick the choicest quotes, even if they don't showcase either boss in the best light.
A "Coldness Rating" will also be assigned based on the harshness of the snipe.
Like Fergie, I'm sure that one day they'll ride off into the sunset together.
The then little-known Arsene Wenger moved to Arsenal in 1996 from Japanese club Nagoya Grampus Eight.
Pundits hailed his intellectual approach to the game, though some were more skeptical, including Alex Ferguson.
"They say he’s an intelligent man, right? Speaks five languages? I’ve got a 15-year-old boy from the Ivory Coast who speaks five languages,” the Scotsman told the media.
Needless to say, the boy from the Ivory Coast disappeared without a trace while the Frenchman led his side to a third place Premier League finish in his debut campaign.
Coldness Rating: Crisp
The following year saw the two increase the number of snipes directed at the other.
Complaining of alleged favouritism by the FA in fixture allocation for the Red Devils, Wenger said, "It’s wrong the league programme is extended so United can rest up and win everything."
Fergie was quick to retort, telling reporters "He’s a novice. He should keep his opinions to Japanese football."
United won the Premier League title in 1997, but it was the Gunners who claimed glory in 1998.
Coldness Rating: Cool
Following three straight years of Manchester United winning the league, Arsenal regained their status as England's no.1 team by trumping the Red Devils in 2002.
In the 2001/02 season the Gunners did the double over Sir Alex's side, eventually sealing the league in a 1-0 win at Old Trafford.
Reeling after a disappointing campaign, Fergie said of Wenger, "He never comes for a drink with the opposing manager after matches. He's the only manager in the Premiership not to do so. It is a tradition here. It would be good for him to accept the tradition."
Perhaps Wenger was too busy celebrating.
Coldness Rating: Piercing
Things between Manchester United and Arsenal came to an ugly head in the mid-2000s.
In the 2003/04 Premier League season Arsene Wenger led his team to the title without losing a match. They were later dubbed "The Invincibles."
Early in the season a missed Ruud van Nistelrooy penalty led to several Arsenal players, Martin Keown being the worst culprit, openly gloating in the Dutchman's face.
In the aftermath, Wenger labelled the striker responsible for the incident, saying "I think Van Nistelrooy does not help himself frankly...he is always looking to dive."
Coldness Rating: Glacial
The next season, it was the Red Devils who ended Arsenal's unbeaten streak, beating them 2-0 at Old Trafford in October.
The match was fierce, but the aftermath was the ultimate in poor sportsmanship.
Tempers flared in the tunnel after the final whistle, with food and drink being hurled at both sets of players. Allegedly, Cesc Fabregas threw a slice of pizza at Sir Alex Ferguson (via The People).
The Scotsman later said of the incident, "Their behaviour was the worst thing I have seen in this sport. They got off scot-free.”
Coldness Rating: Ice Cold in Sir Alex
Months after "Pizza-gate," Sir Alex refused to let the incident die, telling reporters that Arsene Wenger was a "disgrace."
The Frenchman's riposte was furious and unrelenting.
"Ferguson does what he wants and you [the press] are all down at his feet. He doesn't interest me and doesn't matter to me at all. I will never answer to any provocation from him any more," he said.
"He has lost all sense of reality. He is going out looking for a confrontation, then asking the person he is confronting to apologise."
Coldness Rating: Frozen
At some point between 2005 and 2008, something miraculous happened: Sir Alex Ferguson and Arsene Wenger reconciled.
This didn't happen before 2007 though—at one stage, Wenger said he would "never speak about that man [Fergie] again.”
But in 2008, he told the media "There is a much better understanding and mutual respect now.”
Old age was fast approaching for both men, who probably realised there was little to gain in holding grudges.
Coldness Rating: Cool
In recent times, a flare-up between Sir Alex and Wenger is a very rare sight indeed.
The Scotsman has moved on to other foes—namely Rafael Benitez and Roberto Mancini, while the Arsenal boss has had to worry about his side's barren spell without winning a trophy.
In 2009, Fergie said of his former rival, "We have loads of situations now where new managers come in and vanish after a couple of years. It's just the two of us and we'll probably ride out into the sunset together!"
Supporters of both clubs (well, more so United fans) will be hoping that doesn't happen for a few years yet.
Coldness Rating: Glowing