The England international was the cause of two of Bayern Munich’s goals in City’s 3-1 Champions League loss on Wednesday night and has seen his overall performances dip in the past 18 months.
However, teammate Nasri suggests Hart is still right up there with the best glovemen in the world.
"(Real Madrid’s Iker) Casillas doesn't play anymore but for me Joe is in the world's top five, easily.
"I am not worried about him. For the first time in a long time England have a world-class goalkeeper.
"I think that when you are a top player like Joe, you don't have problems with confidence.
"Sometimes you can have a rough patch but he knows everyone is behind him at the club."
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