Fabregas lifted his head up near the halfway line and played a stunning long ball onto the chest of an in-form Diego Costa, who beat Claudio Bravo with his side's first shot on target to cancel out Gary Cahill's first-half own goal.
The Spain international's inclusion in the team was a surprise as Chelsea fans haven't seen him in a blue shirt since their lowest moment of the season - their 3-0 defeat to Arsenal at the Emirates Stadium in September.
It appeared that Antonio Conte had moved on to life after Fabregas, with Nemanja Matic and N'Golo Kante becoming automatic midfield starters, but a muscle injury to the Serbian during the week resulted in the Arsenal old boy being called up for one of the biggest matches of the season.
Willian and Eden Hazard went on to win the game for Chelsea later in the second half, but it was Fabregas's trademark moment that swung the game, with Kevin De Bruyne missing an open net just moments before, while Sergio Aguero passed up a hatful of chances.
That assist was Fabregas's 97th in the Premier League as he trails only three players in the all-time list and it was also his second of the season in only 145 minutes of football, with Arsenal's Mesut Ozil, by contrast, only managing one in his 13 games.
Assists and an incredible passing range are what Fabregas has become known for and he recorded a 90% passing accuracy as he influenced the game against one of the league's toughest opponents.
Conte will be impressed with more than Fabregas's passing as he mucked in, battled and positioned himself well, with Chelsea under pressure for long periods. This will be the most important thing for Conte who spoke of his "trust" in Fabregas before kick-off, despite some labelling him as a luxury player or poor defensively.
Chelsea looked no weaker defensively in the absence of Matic, despite him being more of a specialist in a two-man midfield than Fabregas. It is clear that Fabregas has had to adapt and develop his game to survive under Conte's regime, but today there were signs that he has the fitness and discipline to work between both boxes.
Fabregas is an intelligent footballer who has won everything, but it was also remarkable to see how well he took to the game in Manchester having not played in Chelsea's last eight matches.
He recently needed minutes for the Under-23s to gain match fitness as he had been away from first-team action for so long. It took an injury to Matic for him to get his chance, but Conte can add Fabregas's name to the list of players able to slot into his 3-4-3 system with ease.
He had been linked with moves away from Chelsea to clubs like AC Milan, but this performance may give further motivation for Conte to strengthen his resolve about not selling him, or at the very least, raise his price tag and attract interest from even bigger clubs.
Fabregas kept things a little more simple against City, but it helped the likes of Hazard and Costa shine and his side to get all three points. The 29-year-old can be proud of his role in a second half that was end-to-end as Chelsea outgunned City to remain top of the Premier League.
Meanwhile, Matic could be worrying that he may not be able to instantly stroll back into the starting line-up with Fabregas adapting and excelling for Conte after adding extra industry to his naturally magical passing.
Perhaps it was frustration that caused Fernandinho to grab Fabregas around the neck in added time, earning him a red card, after he saw his midfield opponent punish him in an up close and personal battle at the Etihad Stadium.