Jack Grealish says it has taken longer than he thought it would for him to adapt to a different role at Manchester City than he had at Aston Villa.

It took the England international midfielder less than four minutes to set up Riyad Mahrez for the only goal in City's win over Chelsea on Thursday.

It was one of three assists the 27-year-old has to his name this term -- as many as in his entire first season for City -- but he said he had hoped the goals would flow more freely at the reigning champions.

Grealish made the England World Cup squad despite not having yet lived up to the £100 million ($118 million) fee that City paid for him but was largely reduced to a substitute role by Gareth Southgate in Qatar.

"When I came here, I'll be honest with you, it was so much more difficult than I thought," Grealish told Sky Sports after combined with Mahrez shortly after both were sent on by Pep Guardiola.

"In my head I thought I was going to the team sitting top of the league and I was going to get so many goals and assists and obviously it isn't the case.

"A lot of teams tend to sit in against us and that wasn't the case at Villa."

Grealish has scored just four times since his move 18 months ago, two goals fewer than he mustered in his final season for Villa.

He puts that down to a much more restricted remit in a City side packed with stars than the one he had at Villa where he was the undisputed creative fulcrum.

"(Ex-Aston Villa manager) Dean Smith would tell me to go and find the weak link in the defence, whether that was on the right, the middle or whether I wanted to hug the touchline -- and at Villa, I always had an overlapping full-back," he said.

"I came into City, having been at Villa my whole life, and I've never had to change.

"I've always been used to that. I didn't realise how hard it is to adapt to a different team and manager."