Gary Cahill: everyone thinks Diego Costa is an angry guy but he’s more mature now

• Chelsea captain praises striker after 3-1 win at Manchester City
• City to lose Sergio Agüero and Fernandinho through suspension

Gary Cahill could have been forgiven for fearing the worst when the ball looped up off his shin and over Thibaut Courtois to give Manchester City an interval lead they just about deserved, yet the Chelsea captain was confident his side could rise to the challenge and in the second half they most emphatically did.

That is the steadiness a seven-match winning sequence can bring, although the way Chelsea went about extending that Premier League run to eight spoke volumes about their experience and resilience and raised a few awkward questions about Manchester City, whose frustration boiled over at the end in the touchline fracas that resulted in Sergio Agüero and Fernandinho being dismissed.

“You expect to have to soak up some pressure when you are playing Manchester City away from home,” Cahill said. “They were on top in the first half and went a goal up but it never really rocked us too much mentally. We knew we were still in the game and I thought we played a lot more football in the second half and showed what we can do. Maybe they tired a bit but it was still a very tough game.

“Their team is full of good players, as is ours, but when you get this sort of momentum behind you it is easier to try and keep on winning. Every time we go out it’s a case of ‘we can’t lose this one’, but I think that is a good pressure to have on ourselves. Every individual is working hard and we are playing good football. We are delighted to come through a game like that and take three points from a top side.”

Although Eden Hazard’s last-minute goal put a gloss on the scoreline – it led to many home supporters leaving their seats before Agüero’s blatant foul on David Luiz sparked an unedifying scuffle in stoppage time – the real damage to City had been done by Diego Costa. In the first half he did little except react to a ball-winning tackle by Nicolás Otamendi in such a theatrical way that the defender picked up the game’s first booking.

Then after Kevin de Bruyne had spurned a couple of chances to extend City’s lead to two, Costa turned effortlessly past Otamendi from Cesc Fàbregas’s searching pass to beat Claudio Bravo for the equaliser. City began throwing men forward a little recklessly after that and when Costa received another clearing pass from Fàbregas in the middle of the pitch he held the ball up expertly before releasing Willian to run into space.

“I think we are seeing more composure from Diego this season,” Cahill said. “I know everyone thinks he is an angry guy but you can see a smarter player now. We were starved of the ball in the first half and so was he, and in the last few years maybe he gets frustrated at that. But this time he kept his cool and got more involved in the second half and when he does that he is one of the best going. He has been fantastic this season, showing maturity and still banging the goals in. He’s on fire at the minute and I hope it continues.”

Costa’s impressive form certainly has more chance of continuing than Agüero’s, who is likely to face a four-match suspension, having already been suspended for three matches for violent conduct this season. Agüero is not normally the angry guy, just as Costa is rarely cast as Mr Sensible, but in his defence the City striker did have something to be annoyed about.

David Luiz, the Chelsea player he lunged at in the final seconds, should probably not have been on the pitch at that point. Agüero was denied a clear run on goal in the first half by the defender’s calculated block and while the case for denial of a clear goalscoring opportunity was not quite as black and white, the referee, Anthony Taylor, appeared to duck out of a difficult decision by taking no action and allowing play to continue.

On that occasion City could consider themselves hard done by, yet luck had evened itself out by the interval when Jesús Navas’s habit of regularly hitting the first defender with his crosses paid unexpected dividends in the form of an own goal.

Chelsea were perhaps lucky to still have 11 players on the pitch but City turned round in front and it all unravelled from there. “I will speak with my team about how we handle these situations,” Pep Guardiola said. “We did not lose because of the referee, we lost because we missed chances. It is a problem we have had all season. It is difficult for us to score goals and we concede them very easily.”

Actually, City possibly did lose because of the referee but that does not invalidate Guardiola’s other conclusions. Cahill summed up the difference between the two sides perfectly when he spoke of maturity and mental toughness. Chelsea have those qualities in abundance, which is why they are deservedly on top of the league. City are nowhere near as ruthless or professional. They could not close out the game when they held a lead and when Chelsea established superiority City reacted as impetuously as the supporters who headed for the exits.

Agüero’s suspension will dominate the headlines – City are notoriously overreliant on their leading scorer – although the loss of Fernandinho, for grabbing Fàbregas by the throat, should not be underestimated. The Brazilian was not only one of the home side’s best performers, he has been among the Premier League’s most consistent midfield influences all season. City must go into what Guardiola describes as a crucial period of the season without two key players.