When Jose Mourinho arrived in English football for the first time 12 years ago, he was the new Chelsea manager and the opposition was Manchester United.
When Mourinho returns to Stamford Bridge this evening, it will be the first time he has opposed Chelsea in the Premier League. And his team will be United.
How fickle is the spin of the wheel, the Carousel of the Coaches, in football today.
And how easily do we embrace that illusion that managers might be more important than players.
There could be a billion dollars worth of talent on the field today but how many of those players do you imagine Mourinho spoke about in his many pre-match media interviews?
The answer might be zero.
We are now entering the moment of truth for Mancunians. Are the United fans ready to forget and forego the cavalier style of the Alex Ferguson and Matt Busby eras? Are they willing to accept Mourinho's (picture) pragmatism in place of Fergie's devil-may-care adventure?
To be fair, the questions were all about him. Certainly the answers were.
The Portuguese coach who introduced himself as "a Special One - not one out of the bottle," in 2004 last spoke about any Chelsea player last December when he accused them collectively of "betraying" his work.
He was on the verge of being sacked the second time around by the Chelsea owner Roman Abramovich.
Mourinho's Chelsea won the Premier League three times, and he ended up being fired twice.
This time last year, his team were imploding. Champions the previous season, but rapidly decomposing around him, and he blamed everyone from the club doctor to the star performer, Eden Hazard, for the souring atmosphere. Abramovich acted when there was actually more danger of the Blues going down than retaining their title.
"When some managers leave clubs," Mourinho insisted this weekend, "I don't know the right saying but in Portuguese it is 'wash the dirty clothes'.
"They speak and speak and speak. Mr Abramovich decided to sack me, I left with not a bad word about anybody at the club. This is my way.
"I am there in the history... they cannot delete me from Chelsea Football Club history."
Whoever wishes that?
His successor, Antonio Conte, called it right when he said that the crowd should applaud their former manager before the game, and then regard him as the "enemy" in a football context.
Conte then proceeded at his press conference to address the game, the players, in a way that Mourinho did not.
Mourinho's talk was all about himself. He offered no insight into the line-up, the tactics, the form of players.
No one mentioned the likelihood of Wayne Rooney, captain of United, fighting the apparent dying of his light as a player past the dreaded age of 30. And more than likely a forlorn figure on the bench.
No one addressed whether Juan Mata, whom Chelsea sold on Mourinho's watch to United, will get any game time today.
Conte's musings were different. They were almost all about players, though he did at one point use his own playing experience to illustrate the point that he knows how it feels to be regarded, as N'Golo Kante might, as being a little man in the engine room of Premier League midfield.
Kante stands 1.69m. He weighs around 68kg. At some point in the game, he is likely to come up against Paul Pogba, the relative colossus at 1.91m and 80kg.
Pogba and Kante shared the midfield for France at the Euro championship just a few months ago.
Pogba was coached by Conte at Juventus before Man U paid £89 million (S$151.7 million) for him this summer. Kante was Leicester City's pocket dynamo until Chelsea won the auction to prise him away, for £32 million.
In his case, we know, Mourinho and Conte think the same. Conte asked Chelsea to buy the Leicester ball-winner, the brave interceptor, and won the day despite Mourinho making a personal phone call to try to divert the player's path from his old club to his new.
Right now, as the season begins to unfold, the merit of Kante's choice is undecided. Both Chelsea and United are in transition.
Both have made reasonable but not hugely convincing starts to the season.
Both are still adapting to new management, and to new players purchased in the summer window.
Last Monday, United reverted to Mourinho type by shutting out Liverpool to a goalless draw at Anfield. It was typical "park the bus" tactical straight jacket Mourinho, squeezing the joy out of a highly-rated opponent for fear of daring to play open football.
When Conte, an Italian remember, was pressed on the subject, he responded:
"I think its important to win, but for me also important to win in the right way. Sometimes in the past with other clubs, we won but I wasn't satisfied with the performance.
"I try to transfer these thoughts to my players, always. You must start the game with only one target, to win. Not to play for a draw. I don't like this, it's not football."
But Conte is not a Special One. He is a driven manager whose preferred style is 3-4-3 (three in defence, four in midfield, and three committed to attacking play). Mourinho's Manchester United line-up at Anfield was 6-3-1, hinged on Marouane Fellaini and Ander Herrera covering in defensive roles rather than pressing forward.
We are now entering the moment of truth for Mancunians. Are the United fans ready to forget and forego the cavalier style of the Alex Ferguson and Matt Busby eras?
Are they willing to accept Mourinho's pragmatism in place of Fergie's devil-may-care adventure?
Today at Stamford Bridge they might make an exception. United wins, or even points, at the home of Chelsea have been rarer than blue moons.
Man U won only five of their last 24 encounters at Chelsea - and just once in 14 at Stamford Bridge.
We can hope that today is remembered for Diego Costa vs Zlatan Ibrahimovic. Or Willian against Marcus Rashford. Or whether Hazard is back on form, or Rooney gets a chance to play.
Anything rather than hearing Mourinho repeat that Chelsea won the 2015 title not because of the players, but because he did "an amazing job" making them play above their level.