Pep Guardiola's celebrations with his backroom team when the final whistle sounded on Manchester City's outstanding win at Chelsea underlined the significance of what he had just witnessed.
City won lavish and merited praise for the manner in which they had outclassed Liverpool, Watford and Crystal Palace in their previous three Premier League games, scoring 16 goals without reply.
Outclassing a numerically depleted Liverpool and completing what were made to look like routine thrashings of Watford and Palace is one thing - doing the same to the champions on their own ground off the back of Chelsea's magnificent Champions League win at Atletico Madrid is another.
Manchester City may have only won by Kevin de Bruyne's superb second-half strike to return to the top of the table, but the gulf between these two sides could not be measured by that narrow 1-0 scoreline.
Manager Guardiola's reaction at the final whistle confirmed this was not simply a win but an ominous statement of intent.
Manchester City showed familiar traits as they recorded successive 5-0 home wins in the Premier League against Liverpool and Crystal Palace, with a 6-0 win at Watford sandwiched in between.
All the free-flowing progressive football Guardiola demands was on show as submissive opponents were clinically taken apart by City's variety of attacking riches. It was straightforward work. The scorelines could have been more.
City's win, and its manner, at Chelsea was a different matter altogether. This was a night when they had to dig deep, probe, persevere, show patience.
It was a night to prove, in football terms, that they were not just a pretty face.
And they accomplished the task with such aplomb that, when studied in the wider context, this might well have been the most significant league win of Guardiola's time at Manchester City.
Chelsea looked jaded after their midweek Champions League exertions but there is still an in-built defence mechanism in Antonio Conte's side that makes them fiercely resilient even in extreme circumstances.
And yet, faced with the sort of possession "carousel" Sir Alex Ferguson used to talk of when confronted by Guardiola's Barcelona in the days when Manchester United lost two Champions League finals to his side, Chelsea could not hold on.
Former England striker Alan Shearer told Match Of The Day it was a "seriously impressive performance" by City.
"Even with no Vincent Kompany, Benjamin Mendy or Sergio Aguero, they were better than Chelsea in every single position and dominated the game," he said.
What a difference a year makes
Man City won their opening 10 league and cup games last season before drawing 3-3 with Celtic in the Champions League on 28 September and then losing 2-0 at Spurs on 2 October before the international break
This season, City had won seven and drawn one of their eight league and cup games before their 2-0 win over Shakhtar Donetsk on 26 September and then won 1-0 at Chelsea on 30 September - the last game before the international break Manchester City's 62% possession rate meant Chelsea's 38% share was their second lowest in a home Premier League game since 2003-04, the lowest being 29.6% against Manchester United in a 1-0 win in April 2015.
City refused to become frustrated at the length of time it took to make the breakthrough, confident that they possess the attacking weapons to pierce even the most stubborn defence, which they did after 67 minutes when De Bruyne's left-foot thunderbolt rose past Chelsea keeper Thibaut Courtois.
It gave Guardiola his first win against Chelsea in eight games in all competitions, not including shoot-out victories, after previously losing three and drawing four.
This pleasing statistic will be a minor footnote to the purist and perfectionist.
The Spaniard will have taken as much pleasure in the way City showed their own strength of character to secure this win as he did from the heavy pain he inflicted on Liverpool, Watford and Crystal Palace.
Pep's men show steel as well as silk
Guardiola's first season at Manchester City was undermined by a soft underbelly symbolised by the uncertainty of goalkeeper Claudio Bravo, his replacement for exiled Joe Hart, and the struggles of John Stones following his £47.5m move from Everton.
City's full-backs were all fine club servants but ageing in the shape of Pablo Zabaleta, Gael Clichy, Bacary Sagna and Aleksander Kolarov - and it showed. Guardiola expensively re-upholstered his defence with £50m Kyle Walker from Tottenham, Real Madrid's Danilo for £26.5m and £52m Benjamin Mendy, now possibly missing for the rest of the season with a knee injury.
Here at Stamford Bridge, City produced hard evidence that Guardiola might just be putting the foundations in place to complement those brilliant forwards he has at his disposal.
Goalkeeper Ederson, a £35m signing from Benfica, has already shown his bravery, risking and almost sustaining serious injury in the collision (accidental, it should be stressed) that led to Liverpool's Sadio Mane being sent off during City's 5-0 win at Etihad Stadium.
And, slowly but surely, he is showing the sort of form that suggests he is a good upgrade on the hapless Bravo at Chelsea as he made crucial blocks, commanded his area and showed the calmness with the ball at his feet that Guardiola demands.
Stones, in the absence of injured captain Kompany, also excelled as he was brave in the challenge, cool on the ball and played a full part in a consummate City display.
Just to complete Guardiola's defensive satisfaction, Fabian Delph was one of City's outstanding performers in the unaccustomed role of left-back.
The 27-year-old who stayed to fight for his place won a glowing tribute from his manager as the surprise stand-in for injured Mendy.
"The last few games Fabian Delph has played have all been outstanding performances," Guardiola said. "He is a guy who doesn't lose the ball, is aggressive and clever. I am so happy for him."
The statistics also strengthen the feeling that City are now a more rounded, complete team.
This is the first time they have kept four successive clean sheets in the Premier League since September 2015, during a run of six games. They are currently on a run of conceding only one goal in their last seven matches in all competitions.
"Last season, more often than not, shots on target were going in," Shearer said. "In that department, they have improved. Playing from the back? Not a problem.
"You cannot give them room like Chelsea did. Touch, move, pass, they were simply superb.
"They were pressing and working together to win the ball as a team. Chelsea just could not get out of their own half."
Man City's fearsome five
Sergio Aguero's absence as he recovers from a broken rib sustained in a car crash in Amsterdam would be felt by any club - but Manchester City are better placed than most to cope.
And so it proved at Stamford Bridge as a top-class quintet of attacking talent combined forces to beat Chelsea.
David Silva was the master puppeteer, pulling the strings in midfield with his range of long and short passes, his guile in and around the box, and his experienced game management.
Raheem Sterling was occasionally wasteful but never out of the action while the pace, youthful exuberance and fearless running of Leroy Sane and Gabriel Jesus, both Premier League superstars in the making, gave Chelsea's stretched defence not a moment's peace.
Above it all, rising head and shoulders over everyone else on the pitch, was the brilliant De Bruyne.
It was fitting that another of his spectacular flourishes gave City the win they deserved, a searing left-foot finish that you could hear as well as see, a goal from the moment it left his boot.
De Bruyne has had a direct involvement in 15 goals in his past 17 Premier League games, with three goals and 12 assists. Nine of his last 11 goals for City in all competitions have come from outside the box.
The 26-year-old Belgian, who punished the club he left for Wolfsburg in a £16.7m deal in January 2014 after making only three Premier League appearances, is arguably the most influential forward in the division.
"He can do absolutely everything," City boss Guardiola said.
"With the ball he is a guy who can play different positions, go to the channels, assist long or short.
"After, without the ball, he is the most humble and shy guy. He says if he has to run 100km for the team he will do it. It's not easy to find that with kind of talented players."
Guardiola, so often agitated and intense in his technical area, cut a relatively relaxed post-match figure. De Bruyne is one of the reasons why.
Guardiola must heed note of caution
Manchester City stand top of the table with 19 points from seven games - only Everton have escaped unbeaten after a 1-1 draw at Etihad Stadium.
City look in imperious form but the experiences of last season and the magnificent form of those who will challenge them for the title will temper any over-optimism, not that Guardiola will allow the slightest whiff of complacency.
Manchester United's relentless march continued on Saturday with another 4-0 win, this time against Crystal Palace, and they are only behind City on goal difference, with the pair five points ahead of third-placed Spurs.
Arsenal, Chelsea and Liverpool will hope to exert pressure but look a level below City and United.
Guardiola will remember, though, when a 2-0 loss at Spurs almost exactly a year ago spoiled City's perfect start and opened up cracks.
This season they are more impressive in all areas in the Premier League at the same seven-game stage. They have one point more on 19, they have scored 22 goals compared to 18, and conceded only two compared to seven.
Guardiola will have learned the lessons and will hope to avoid the pitfalls this time around.