After winning the battle with Shay Given to be Blues' number one this term, Hart has enjoyed a stellar campaign. The 23-year-old has managed 22 clean sheets in his 45 appearances for City this term, leaving him just four short of Nicky Weaver's club record.
In addition, Hart has secured the number one berth for England, winning his 10th cap in Tuesday's friendly draw with Ghana at Wembley. Clearly, the Shrewsbury-born star still has a lot of improving to do, which is why Mancini is so sure he can become one of the best.
"Joe Hart could become one of the top English keepers in history,'' Mancini said. "He is young and he is strong. Like everyone, he makes mistakes but that is normal when you are young.
"Maybe sometimes he worries too much when he has the ball. But he is getting better with every game. Also, you have to remember, this is the first year he played for a club who were competing for the title.
"Last season was the first time he played for a full year in the Premier League, with Birmingham. He is already a fantastic keeper and he can still improve a lot.''