The Blues gifted the visitors a soft equaliser after Courtois' lapse of concentration saw his poor clearance fall straight at the feet of David Silva.
The Spaniard fed Sergio Aguero, who slotted home from close range in the 26th minute.
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Wed, April 5, 2017
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Thibaut Courtois – 5
Thibuat Courtois was punished for his costly mistake against Man City
Eden Hazard refused to blame Thibaut Courtois for his error
He made a great save – he made a mistake with the goal, but it was not his fault
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But Hazard insists Courtois wasn't at the fault of his goal.
When asked about the Belgian's role in the goal, Hazard said: "No Thibaut is Thibaut.
"He made a great save – he made a mistake with the goal, but it was not his fault.
"We are lucky to have him."
Chelsea's victory meant they maintained their seven-point cushion over Tottenham at the top of the table.