The 26-year-old was singled out by former City manager, Roberto Mancini, after a string of poor displays, and was at fault for Scotland's opener in the Three Lions' recent 3-2 win at Wembley.
More uncertainty followed in a shock 3-2 loss to Premier League newcomers Cardiff City, but Milner insists Hart is not struggling for confidence in training and the squad are completely behind him.
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"He’s a victim of his own success because of how good he’s been and how quickly he’s become England’s No.1 and playing for Manchester City. People said he had a poor season last season but he won the Golden Glove.
"Some of his performances and the saves he made last season ... the Dortmund game stands out. We could have lost 8-1 very, very easily. It was one of the best goalkeeping performances I’ve ever seen. In training you can see he’s not struggling for form or confidence.
"He knows what comes with being England’s No.1. With City and England you get to the top and you’re there to be shot down.
"He’s mentally strong enough to deal with that but we’re all human beins and if the players around him can give him a gee-up, even if he doesn’t need it, that will help."
City manager Manuel Pellegrini recently warned Hart that he needs to rediscover his form if he is to remain first choice at the Etihad Stadium, and Milner has backed him to turn the corner and grow from the experience.
Milner continued: "He’s still putting in performances for us and he might make the odd mistake but you’ve got to remember he is still pretty young in goalkeeping terms.
"If this is a so-called ‘blip’ in form – which it may be because his standards are so high – then he’s only going to come out of it better mentally. He will become an even better player for having this."