Samir Nasri capped a stunning Manchester City comeback as they set a new Barclays Premier League record with a 20th consecutive home win.
Carlos Tevez who returned to the team after six months in exile since his Munich bust-up with manager Roberto Mancini, produced the pass which put the spark back into Manchester City’s title bid.
Tevez came in, in place of Nigel De Jong to more cheers than boos.City fans might not like what he has done but they are a forgiving bunch.
Chelsea had enjoyed a resurgence under caretaker-boss Roberto Di Matteo, winning four games in a row since he took over from the axed Andre Villas-Boas.
They left no one in doubt of their mission from the start.
Chelsea had threatened to dent their title hopes when defender Gary Cahill put them in front with a right-foot shot that took a slight deflection.
The home team drew level later from a beautiful spot kick taken by Aguero after Essien arms stopped a Pablo Zabaleta volley at close range
Nasri arguably played his best game since his £24million summer arrival from Arsenal, City were unlucky not to take the lead on eight minutes.
More brilliant flashes from the former Arsenal man, then he is set up by Tevez and he neatly puts in the ball to give his side the needed three points to keep their title dreams alive.