COMMENT: First the praise - the warning can come later. As a riposte to the Einsteins out there, Jose Mourinho couldn't have said it better himself.
Four goals before halftime. Against the champions. A first-half not seen by Manchester United fans since 2006 (against Fulham). A performance not seen since the best days of Sir Alex. Crisis? CRISIS? What crisis?
Let's get the black marker out and tick them off together:
They said he couldn't work out where to fit Paul Pogba. But, again, there he was, scoring his first goal for the club and pulling the strings in midfield.
They said he wouldn't work with Juan Mata. The same Mata who was also on the scoresheet, outstanding on the day and name-checked by Mourinho in the post-match.
They said he'd killed off Jesse Lingard's career. But the local lad was recalled and turned in a superb performance for his manager on the day.
They said Mourinho's football just wouldn't appeal to United fans. Erm, you can scratch that one off. United were irresistible at times. You couldn't look away.
And they said he'd lost his bottle and could no longer make the tough calls. But he benched Wayne Rooney - so much for that.
Chelsea are big. Real Madrid massive. But United are something else. The scrutiny for a manager is unlike anything in football. Mourinho, for all his experience, has never seen his career pulled apart like its been over the past fortnight. He's kept strong. And the board made it clear, even before the EFL Cup win at Northampton, that there were no doubts about his appointment. But it's been a unique fortnight in the life of Jose Mourinho.
Saturday was a response. A chance to meet the doubts raised - one by one - and dispel them. And while there'll be plenty written and said about Pogba, Mata, Zlatan Ibrahimovic and Daley Blind, the most significant contribution on the day, for Mourinho especially, came from Lingard.
The derby was a shocker. The worst 45 minutes of Lingard's first team career. And it had to come against Manchester City. Pep Guardiola's Manchester City. He tried, did Jesse. He huffed. He puffed. But nothing clicked. The ball was bouncing off ankles. Off shins. Rolling over his foot. It was ridiculous. But Lingard hadn't suddenly become a bad player. It was just one of those days. A game that so many pros experience. Mourinho hooked him at halftime. That was three weeks ago. And it wasn't until Saturday when Lingard was seen again.
There was real concern that this was it for Lingard. He'd been tried by Mourinho and failed. He was one of those, it was claimed, the manager was questioning when discussing mentality. Lingard had fluffed his lines. Flopped on the big stage.
Which is why his performance against Leicester was so significant. On the ball he was direct. Off it, he was aggressive. This was a completely different player whom some at Old Trafford had turned on against City. Mata's goal was a beauty. The pick of the four. And Lingard was at the heart of it.
They said Mourinho wouldn't choose wide players. He'd ignore the locals. Yet, the manager, facing a third consecutive league defeat, put his trust in Lingard. Mourinho can't adjust? He won't change? John Terry apart , when did he back a Lingard or Rashford at Chelsea? Seriously, can we stop with the Jose cliches?
Now the warning.
In the post-match, Mourinho volunteered his check points of how to build a successful team. There was little prompting from the interviewer. He talked about playing principles, about the dynamics between players and then, finally, mentioned consistency in performance. Mourinho was essentially warning fans that, as good as Saturday was, there'll be relapses into the old ways. The consistency isn't going to be there a month into a new season.
Indeed, it can be argued that Saturday wasn't United's best performance of the campaign. That came on Paul Pogba's debut against Southampton. The Frenchman, himself, admitting as much when declaring on Saturday that the display against Leicester was his "best since the international break". Against the Foxes, the first-half was one to treasure. But against the Saints, over the full 90, the promise United offered was so much more.
In terms of big spending, United haven't seen the like for 27 years. In 1989, Sir Alex Ferguson went out and signed Neil Webb and Mike Phelan - and was rewarded on the opening day with four goals against the champions Arsenal. But the team then collected one point from the next four games and so Fergie went again, buying Paul Ince, Danny Wallace and Gary Pallister. And with all his new stars together, they put five past Millwall. But that season, while lifting the FA Cup, they finished thirteenth. However, the buying spree laid the foundations for Fergie's first great team of his era - and we say the best.
Today, Mourinho's United look far from a 13th placed team. And he's a much better manager than Fergie was at that stage. But newly built, hastily put together teams are always going to have their off days. Even their off weeks.
The pitfalls will arrive. This team will stumble. But there's a plan fans can see. Mourinho's project is developing in front of them. Just like Fergie all those years ago, he's building something.
All he needs from those who waver at every inevitable slip, is a bit of faith.