The Italian is a firm believer in the 24-year-old's quality, but was unsuccessful in bringing him to Eastlands during the summer transfer window.
Mancini admitted his frustration at failing to sign the player, and according to reports in talkSPORT, sighed: "I have followed him since his days at Pisa in the 2007/08 season. He was just 20 but immediately did things that were extraordinary.
"He is one of the few players who are able to win a game on their own. If I could have I would have brought him to the Premier League a year ago.
"We have tried again this summer because I thought he might make an important contribution and mix well with the players here at City.
"But we could not complete the transaction and in all honesty I must say that I understand Fiorentina", the City manager groaned.