Carlos Tevez made his first appearance for Manchester City since September and set up Sami Nasri's 85th minute winner as they came back to beat Chelsea 2-1 at Etihad Stadium.
Roberto Di Matteo's men had looked on course for a win as Gary Cahill's deflected effort on the hour gave them the lead.
Then with just five-minutes left, Tevez picked up the ball on the edge of the box and he played through a wonderful ball for Nasri to latch onto and finish past Cech.
The win means City are now back to within a point of leaders Manchester United and they have now set a new Barclays Premier League record of 20 successive home wins.
Both sides had come into the game with central defensive problems.
In the absence of Vincent Kompany and Joleon Lescott, Roberto Mancini solved his by moving Micah Richards into the centre as Kolo Toure's partner and picking Pablo Zabaleta at full-back.
Chelsea were more straightforward as Cahill and David Luiz were given the job of subduing Mario Balotelli and Aguero.
The best chance off the first chance came when Nasri took down Yaya Toure's long pass magnificently on his chest, before lifting his first-time shot over Petr Cech, only to see it come back off the bar.
Their next clear sight of goal did not come until the half hour mark, and then the architect was a member of the opposition.
Lampard was not thinking as he rolled a pass along the halfway line and Mario Balotelli seized possession and raced forward to leave the Chelsea defence streaming back in his wake. However, Cech showed all his experience, staying tall and making the young Italian decide which way to go. Balotelli went left and Cech dived to push it round for a corner.
In replacing Balotelli with Gareth Barry at half-time, Mancini was aiming to fill the midfield.
As the second-half bubbled on, it was only a matter of time before the opener arrived. But no-one expected it to come at the other end.
City felt Luiz should have been penalised for a shove on Barry but referee Mike Dean ignored the protests, which allowed the ball to run on for Cahill.
His shot would have been saved by Joe Hart without the massive deflection off Yaya Toure that left the City keeper totally stranded.
That was the trigger for the arrival of Tevez. For so long as the row over his non-appearance in Munich last September rumbled on, it seemed he had no future at the club. Against all odds, he is still here.
And while the Argentinian still looks like he could lose a pound or two after his extended career break, he retains the ability to make an impact.
It was his pass to fellow substitute Edin Dzeko that earned the corner from which Michael Essien handled Zabaleta's shot.
Aguero is now City's number one Argentinian penalty taker and he coolly sent Cech the wrong way.
But Tevez was not finished. With five minutes left, he collected Nasri's pass on the edge of the area, turned and nicked the ball through to his team-mate, who had continued his burst into the box.
This time Nasri found the finish too, cheekily nicking the ball over the advancing Cech to send the stadium into uproar and breath fresh life into City's championship challenge.
