Manchester City 3 Chelsea 0

It was a win, one imagines, the entire medical profession will toast. Well, apart from the two physiotherapists in Chelsea colours who came on during the first half, dropped some of their equipment, missed the fact there were two injured players rather than one and gave Manchester City’s gloating supporters the chance to add to José Mourinho’s serious discomfort on the touchline.

Mourinho might have to understand if the loud, cackling cries of "sacked in the morning", followed by chants in favour of Dr Eva Carneiro, become a regular soundtrack wherever Chelsea play this season. Nothing, however, will have irritated him more than the way his players crumpled in the face of sustained excellence from Manchester City. Nobody should assume it was connected to a week of damaging headlines but it must be disturbing, nonetheless, for Mourinho that his team are five points behind already and locked in a game of catch-up against the side that have just subjected them to a rare, old-fashioned beating.

Chelsea have shown their staying power before and nobody should be knee-jerk enough to write them off when there are still, lest it be forgotten, 108 points available between now and the end of the season. Yet City are clearly going to be a difficult team to overhaul and, even at this early stage, the five-point gap that has opened up between the two sides feels like a sizeable advantage. Two weekends into the new season, it is way too early to form any lasting judgments about how the title race is going to pan out. It has, however, been long enough to see that Manuel Pellegrini’s team are going to make a much better fist of it than last time.

Pellegrini must have wondered whether his job was safe earlier this year but his team have started the current campaign in a way that makes it feel all the more perplexing that they could not have challenged Chelsea more tenaciously last season. It was rare to see Mourinho's team opened up with so much frequency and even ignoring, for one moment, the goals from Sergio Agüero, Vincent Kompany and Fernandinho, a bumper crowd of 54,331 – on the day City opened the new South Stand – could also reflect on at least four presentable chances before the scoring started.

Agüero seemed locked in a personal dual with Asmir Begovic, deputising for Thibaut Courtois in the Chelsea goal, until that moment just after the half-hour mark when the Argentinian showed his expertise inside the penalty area. He is a brilliant finisher but this was a day when he also showed his qualities of perseverance. He was a constant menace and if Agüero can stay fit this season there can be no doubt City have the most capable striker in the league.

Chelsea have a formidable centre-forward of their own in Diego Costa but the difference between the two was laid bare here. Agüero spent the entire match trying to find a legitimate way past the Chelsea defence, always looking for space and a chance to draw back his shooting foot. Costa, on the other hand, seemed entirely preoccupied with winning free-kicks, throwing his hands in the air in barely plausible outrage and trying to pick fights that, for the most part, were only in his imagination. There was an element here of good versus bad and City Costa, to give him his due, was entitled to be aggrieved by the clattering elbow that left him with a bandaged head towards the end of the first half and Fernandinho, perhaps fortunately, being shown a yellow card rather than a red. The origins, undoubtedly, lay in a disagreement shortly before when Costa seemed to be doing everything possible to provoke some kind of confrontation. Then, at half-time, there was the pantomime of him shaping to get to Fernandinho in the tunnel while his team-mates tried to block him off.

What Costa could not do was make any lasting impression on a City defence where Kompany is showing improving form and Eliaquim Mangala looks far more comfortable than in his first season at the club. Yaya Touré looks rejuvenated and Raheem Sterling has given City a new way to penetrate defences on the left side of attack.

Kompany's goal was a header from a David Silva corner, just like it was at West Brom last Monday, and the shot from Fernandinho to finish off the scoring after 85 minutes was beautifully taken.

Agüero had run clear of Chelsea's strangely disjointed defence inside the opening 30 seconds and, having been unable to take the kind of chance he normally accepts blindfolded, his goal came almost out of nothing. Agüero might have had his back to goal when he took Silva's pass but there is always an air of menace any time he has the ball inside the penalty area. His mind is always working out the angles and how to manoeuvre the space to get his shot away. The quick exchange of passes with Touré, no more than six feet away, put him on the move but it was the change in direction that did the real damage. Gary Cahill could not keep up with him and Agüero always seem to have that rare knack inside the penalty area that he never rushes his shot.

Begovic had already denied him on three separate occasions in the opening half an hour but this time Agüero, on his left foot, went for precision rather than power, taking another little touch to steady himself then rolling a shot expertly past the Chelsea goalkeeper and in off the post.

(Guardian service)