Pep Guardiola's side will go within three points of the Gunners if it defeats them in a titanic showdown at Etihad Stadium next week, and it still has a game in hand to come after that.

Things were far from comfortable for them in the first half, but a second-half masterclass inspired by Rayan Cherki helped City pull clear against Chelsea.

The Blues had the better chances in the early stages as Cole Palmer and Joao Pedro lashed into the side netting, while Marc Cucurella finished across Gianluigi Donnarumma, but he did so from an offside position.

City's only real opportunity of the first half saw Robert Sanchez deny Bernardo Silva from close quarters, but it was a totally different game after the interval as the visitors upped the ante.

O'Reilly met Cherki's cross with a towering header past Sanchez in the 51st minute, and only six minutes later, the Frenchman provided an even better assist, gliding across the box before slipping a neat pass into Marc Guehi, who finished like a centre-forward.

It was game over when Moises Caicedo was caught in possession by Doku, who advanced into the area before finishing inside the near post in the 68th minute, and Donnarumma preserved his clean sheet with a late stop to keep out Cucurella's header.

Doku did not shy away from the importance of the upcoming Arsenal clash when speaking after the game. 

"First of all, we need to recover now, and then we'll analyse Arsenal again," he said. "I'll look at what my task will be, and their weaknesses and their strengths.

"Then we'll believe; we did it already. They will come with hunger; they don't want to just give it to us, so we have to take it. Trust me, we'll be well-prepared."

Asked if City's next game was a title decider, Doku said: "I think so, yeah. There are six or seven games left. If you win this game, it's a big punch towards them.

"If we lose, it's in their hands, and we have to wait for them to lose. But if we win, it's in our hands. I would prefer to have it in my hands."

Chelsea boss Liam Rosenior took accountability for Chelsea's loss.

"Not good enough in the second half. We didn't start well," he said.

"Had moments to clear the box and keep the ball, but we didn't. They were camped in our half for the first five minutes, and then we concede a goal.

"Then it's a similar story for the past month now in terms of dealing with setbacks.

"I am accountable. This is a group. It's something we need to improve. It starts with your habits and values. I can't say there was a lack of effort.

"But there was a lack of confidence in the second half. We have to improve. We are in a difficult place at the moment, and we have got another huge game next week [at home to Manchester United]."

Chelsea waas without Enzo Fernandez for the second game running, after his suggestions that he could leave the club after the FIFA World Cup, while hinting he would like to join Real Madrid.

While he apologised after the FA Cup clash with Port Vale, Fernandez was not reinstated to the squad, and Rosenior admitted he was a big miss.

"Any team will miss Enzo," he added. "Myself, backed by the leadership group and sporting directors, made a decision for the long-term of the club.

"There's nothing personal with Enzo. He will be back with the group on Tuesday. He is a top, top player and a really good guy. Really looking forward to having him back."