Pep Guardiola's side enjoyed a successful outing at Kenilworth Road to book their place in Wednesday's quarter-final draw.
Erling Haaland netted five goals in the dominant victory, with Kevin De Bruyne providing assists for each of the Norwegian's first four efforts.
Mateo Kovacic also got on the scoresheet to take Man City's tally to six, as the holders continued their FA Cup defence with a comprehensive win.
However, Man City's evening was soured by an injury setback for Grealish, who had to be withdrawn in the 38th minute due to an injury issue.
The England international was consoled by his teammates as he made his way off the pitch, before he covered his head with his tracksuit top as he sat down on the bench.
Grealish was making his first start since returning from a groin injury he picked up in the Champions League win over Copenhagen earlier this month.
Speaking to reporters after the match, Guardiola indicated that Grealish had suffered a reoccurrence of the same groin issue.
Guardiola said: "I didn't speak to the doctor but he complained a little bit about the groin, maybe it is quite similar. He felt really really good but unfortunately, he got injured. It's been a tough season for him, he has to recover well."
Tuesday's early withdrawal represents the latest setback in a difficult campaign for the 28-year-old, who has struggled to nail down a consistent start place this season.
Although he has featured in six Champions League lineups, Grealish has had to settle for just seven starts in 14 Premier League appearances.
The winger is now a doubt for Sunday's Premier League clash with local rivals Manchester United at the Etihad Stadium.
England boss Gareth Southgate will also be concerned over Grealish's fitness, with the Three Lions set to play Brazil and Belgium in friendlies next month.