The £50million frontman missed a sitter, set up Andre Schurrle's opener, hit the crossbar and then netted the decisive goal - his first Barclays Premier League goal of the season and second of 2013 - after Sergio Aguero's stunning equaliser.
Jose Mourinho: "When a striker misses an easy early chance, many times he's affected for the rest of the game.
"It looks like that moment was the moment where Fernando thought 'I will be the man of the match'.
"The goal comes in a very intelligent action by Fernando. (A) misunderstanding by Joe and Nastasic, but Fernando was very clever.
"He's sharp, he's powerful, the belief is high.
"We are happy for him, but we are all happy because it's a very important victory against a team we couldn't beat last year."
Source: Manchester City MAD