During those wild days of mid-September when Jose Mourinho was shown the door, perhaps Sir Alex Ferguson offered the most insightful comment. Asked about Chelsea without The Special One, Ferguson said they would still have the same players. In other words, Drogba and Lampard wouldn’t stop scoring goals; Carvalho, Terry and Cech wouldn’t stop saving them.

Trapped in the wrong place on the wrong afternoon, poor Manchester City are now fully aware that good players remain good, regardless of who sends them on the pitch. And so an afternoon at Stamford Bridge in search of answers about City ended up offering us fresh ideas about Chelsea. Like a wanton boy swatting a fly, they killed City with a ruthlessness that was cruel. If this is how Chelsea mean to continue this season, they will be right there at the end, challenging for everything.

Were Chelsea as good as 6-0 suggests? They were. Did they tear City apart limb by limb? They did. A man who attends every Chelsea game, home and away, sat in the next seat and judged it Chelsea’s best performance since the 4-1 defeat of West Ham in April, 2006. That’s 18 months and a lot of games under the reign of Jose.

Avram Grant speaks endlessly of wanting to consider the future, not the past, but there is no getting away from Chelsea’s recent past. “The thing is, we loved Jose,” a Chelsea supporter said dolefully as we walked to the ground. So, consider the significance of yesterday’s result. Chelsea never scored six under Mourinho in the Premier League and in his final full season at the club, they didn’t often play with the sustained intensity that overwhelmed yesterday’s opponents.

City are not a bad side and there was no fluke about their excellent start to the season. Third in the table, there had been loose talk about a Champions League challenge and hints that they might be the team to end Chelsea’s three-and-a-half-year unbeaten home league record. Pie in the sky-blues, you could say.

Chelsea were quick, sharp, energetic and fiercely determined to put City to the sword. Then, they twisted that sword and it had to have been about the longest 90 minutes of Sven-Göran Eriksson’s managerial career. Before yesterday, his biggest defeat has been a 5-1 loss to Arsenal when he was manager of Gothenburg.

Eriksson came to Stamford Bridge with the appreciation of the football world. He has turned City into an exciting side. No longer are they scavenging for one-nils, because with Martin Petrov and Elano, they now have creators and scorers in the midfield. But yesterday was a day of reckoning and City were rather like a deer caught in the head-lamps, blinded by Chelsea’s speed and accurate passing.

Petrov and Elano can play, but so too can Mikel, Lampard and Michael Essien. The difference was that Chelsea’s midfielders do it at both ends of the field. They attack and they defend. City’s two most creative players don’t do much defending. Therein lay the imbalance – all Chelsea players were prepared to accept every responsibility.

There was even a heart-warm-ing moment when Essien was fouled by Elano. He could have gone down and in this sometimes cynical modern age, you expected it, but he carried on. His pass to Drogba was excellent but the striker’s touch was uncommonly heavy and the chance was lost. Essien turned and raced back to his position, never uttering a word of complaint nor pointing any finger at Elano. Referee Mike Riley took it all in and as he passed Essien, he gave a warm pat on the back. Mike, you spoke for all of us.

What was most impressive yesterday about Chelsea was the hunger for excellence. They didn’t want to simply beat City, they wanted to deliver a special performance and they were intent on sending a message to Manchester United, Arsenal and Liverpool. Lampard was magnificent, playing with the zest and sharpness that can make him such a terrific midfield player. As much as Drogba, he terrorised the City defence, constantly getting into scoring positions.

He set up the first two goals and it was interesting to watch Roman Abramovich as Riley sounded the half-time whistle and sent Chelsea to the changing room with their two-goal lead. Standing from a seat in his corporate box, the owner smiled and applauded. This, you knew, was the kind of football the boss wanted. The owner’s day would have been completed by the sixth goal, scored by the replacement, Andriy Shevchenko.

In the dugout Avram Grant sat with new coach Henk ten Cate, and it was interesting to watch the two. Ten Cate wore a suit and didn’t have the quiet body language of, say, Steve Clarke. He gesticulated, he occasionally caught the attention ofa Chelsea player and delivered a tactical message. With his Dutch confidence and assertiveness, he will make an interesting No 2.

And what of the unlikely Grant? His record is beginning to look half-decent but there was no chant from the Shed for the unlikely one. “It is not easy to sing my name. Try it, it’s Israeli,” he said afterwards. But the score and performance produced lots of singing from the faithful and Stamford Bridge was a passionate place yesterday afternoon.

As the players trooped off at the end, each shook the hand of Grant. Not warm, not cold, just respectful. Except one. As Shevchenko came past, he stopped and hugged Grant. It was an interesting little moment at the end of a very interesting, and entertaining, afternoon.