Chelsea's Incredibles storm the citadels

Cruyff's 'boring' barb comes back to haunt him as Mourinho's men begin conquest of Europe

It has been evident for some time that the balance of footballing power in London is switching from N5 to SW6 - not, alas for Mohamed Al-Fayed, that Fulham have anything to do with it. To the special delight of those with a greater sense of English sporting history than Chelsea's current owners, the formal transfer of power, and the Premiership title, could even take place on the Wednesday night next month when the reigning champions, Arsenal, visit Stamford Bridge.

With a game in hand at home to West Bromwich Albion on Tuesday, Jose Mourinho's side ought to be going into Easter at least 11 points ahead of the field. Should Manchester United or Arsenal slip up next weekend, it could be even more. Better, really, to get used to the idea, rather than cling to Arsène Wenger's illogically defiant assertion that "the championship is not over".

What now seems an irresistible process began, appropriately, with the onset of a new Champions' League campaign in mid-September, and was confirmed as such over the course of the past week when Arsenal's run ground to its annual halt. Six weeks into the season, the champions were not only heading for an unprecedented record of 50 unbeaten League games, but sweeping all domestic opposition aside in glorious, free-scoring style. Chelsea, meanwhile, were drawing premature criticism for the miserly quality of their football and their 1-0 wins. Yet as soon as the teams moved on to a broader stage, Wenger's cast developed a familiar stutter, with victory by an own goal over PSV Eindhoven and an edgy 1-1 draw at Rosenborg; Mourinho's men found their voice, and their form, producing three-goal bursts against Paris St Germain and the European champions, Porto.

For each side there was a carry-over into domestic football, and by the start of November Arsenal, held to two further European draws, had also lost their unbeaten Premiership record and their lead at the top to a Chelsea side inspired by the fully fit Arjen Robben. So the trend has continued right through last week's dénouement, by which time the new character of each team was clearly visible. It was as if the cavaliers and roundheads had swapped identities.

No wonder there was confusion in Catalonia, where Johan Cruyff and others claimed to have seen a vision of the death of football, with Mourinho as the Lord High Executioner. Perhaps Cruyff has had his satellite dish stolen, or cannot in his contempt bear to watch Premiership football; whatever the reason, his characterisation of Chelsea, absurdly based on 90 minutes of the first leg in Barcelona (when Mourinho's side had to play for a third of the game with only 10 men), as obsessed with defence certainly provided the spur for Tuesday's truly astonishing first quarter.

Home supporters asking: "Rijkaard, Rijkaard, what's the score?" might more relevantly have addressed the query to his revered countryman. As Eidur Gudjohnsen put it much later in the evening: "A lot of people did a lot of talking, but the only way to get your point across is on the pitch. The only answers are out there."

The second leg showed the other side of Chelsea - a much truer depiction - and of Mourinho. Familiar enough with the realities of modern football to know that a wise coach builds his house upon the rocks of solid defence, he allowed the inhabitants sufficient scope to expose Barcelona's hacienda as one built on sand, which it required the genius of Ronaldinho to repair. Mourinho was brave to put his faith in Mateja Kezman and typically astute to construct a new line behind him, with Gudjohnsen thrusting down the middle behind Kezman as the most aggressively attacking of central midfield men. Within eight minutes, Kezman had pulled wide and crossed perfectly for the Icelander to supply an early, uplifting goal.

Then there was Joe Cole, about whom the manager has had serious doubts in the past, first hinted at on last summer's American tour, when he mused publicly about how to find a regulated role for a free spirit. In successive games against Liverpool, Norwich and now Barcelona, the much-derided Cole has been outstanding, showing new discipline and awareness without losing his creative verve; and in a position by no means ideal for him, wide on the right. Even Sven Goran Eriksson, hardly a natural fan, has been moved to admit: "You have to sit up and take notice."

Of course, there is one rider to all this, concerning John Terry's winning goal, which could not have stood if Pierluigi Collina had had a better view of Ricardo Carvalho's foul on the goalkeeper. Wenger was quick to point out the following night, after his side had failed by one goal to join Chelsea in the quarter-final: "It's all on the smallest details that are impossible to predict. If the referee gives a free-kick, Chelsea are out." Similarly, if Oliver Kahn had not reached Kolo Touré's late header, Arsenal would be in Friday's draw instead of Bayern Munich.

So, yes, everything is in the detail. But sometimes even the scoreline lies, and sometimes it tells a wider truth. This time it told us that Chelsea had beaten a team superseding their oldest enemies, Real Madrid, as the most naturally gifted at work today, while Arsenal had fallen well short of their European target again. Wenger, initially pleading bafflement when asked the reasons for his club's continual failure, later suggested injuries and bad defending - the two defects being related in the case of Sol Campbell's absence, just as they were once United lost Rio Ferdinand a year ago.

The Brazilian central midfielders Gilberto Silva and Edu, both absent for long periods, have been missed more than might have been expected, partly because replacements such as Cesc Fabregas and Mathieu Flamini were too young and inexperienced to sustain their outstanding early promise; similarly with Jose Antonio Reyes and Robin van Persie, whose immaturity has been compounded by the indifferent form of Fredrik Ljungberg and Robert Pires. Patrick Vieira, interestingly, was missing for the first four games of the season, which produced 16 goals and some dazzling football. Since returning, he has been barely a shadow of the old driving force. Now comes an additional test rarely faced, in the shape of injury to the mercurial Thierry Henry.

"The Invincibles" have peaked. Chelsea have continued on their upward curve, not just because of expensive investment, but also thanks to better coaching, organisation and, as Gudjohnsen suggested, individual improvement. Having finished above Arsenal once in the past 18 seasons, they are about to improve on that dismal record. London may be the first citadel to fall, but will not be the last.