By the time Hart won his fifth cap, against Bulgaria on Friday, the England boss was looking at a very different goalkeeper.
'When I selected him two years ago he was not the same,' said Capello.
Step up: Fabio Capello believes Joe Hart's attitude has changed for the better
'He did not have the same focus on the games or the training. He probably started to play in the first XI too early and started to think, ''I am the best''.
'You have to understand, sometimes this happens in the mind of the young player. But in two years he has come back. The most important thing is the quality of the player.'
Hart was brilliant against Bulgaria on Friday. He was a formidable presence, making vital saves, and his role in the 4-0 win was as important as hat-trick hero Jermain Defoe's as he made three key saves at 1-0.
Big impression: Joe Hart's performance against Bulgaria was equally as impressive as Jermain Defoe's hat-trick
It is hard to believe it was the 23-year-old's first competitive game for his country.
When Capello was asked if he had come to regret not picking Hart in the World Cup finals, where he was behind Robert Green and David James, the Italian bristled and swerved the question.
'He improved a lot last year when he played at Birmingham,' said Capello.
'He improved a lot because of one season in the Premier League. He played every game and that was really important.'
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