Back to keep on Reds’ tail
De Bruyne had a repeat opportunity moments later only to fire over, but Mahrez stepped up to put City ahead with a fine individual goal.
The Algeria international cut inside from the left between two defenders and sent a low shot through the legs of Tomori and into the far corner of the net.
It might have got worse for Chelsea as Kepa gifted another chance to Aguero in front of goal but the Argentinian thumped his shot against the crossbar.
Mahrez went close to grabbing a second after the break following another run across the box but this time he clipped his effort wide.
Mahrez was unlucky again after Cesar Azpilicueta produced a fine block to deny Fernandinho and the ball dropped to him, but this time Kepa touched his powerful drive over.
Phil Foden looked lively after he was introduced for David Silva – who was suffering from cramp – in the 67th minute but his first effort saw him shoot tamely at Kepa.
Aguero wanted a penalty after tangling with Reece James on the edge of the area, but nothing was given.
Aguero may have been hurt in that fall as it proved to be his last meaningful involvement and he limped off soon after.
For all City’s control in the second half, they did not kill off the game and they had scares when Willian volleyed over and Mason Mount curled an injurytime free-kick wide.
Ederson 7; Cancelo 7, Stones 7, Fernandinho 8, Mendy 7; De Bruyne 8, Rodri 6 (Gundogan 52, 7), David Silva 7 (Foden 67, 6); Mahrez 8, Aguero 7 (Jesus 77, 6), Sterling 7. Unused subs – Bravo, Walker, Angelino, Otamendi.
MAN CITy:
CHELSEA:
Arrizabalaga 7, Azpilicueta 7, Zouma 6, Tomori 6, Emerson 6 (James 59, 6), Kante 8, Jorginho 7 (Mount 74, 6), Kovacic 7; Willian 7, Abraham 6 (Batshuayi 73, 6), Pulisic 6. Unused subs – Caballero, Christensen, Pedro, Giroud.