Injuries and suspensions often interrupted the Italian's first two years at the Etihad Stadium, while this season he has managed just the one goal from a total 13 appearances, including seven starts.
Toure recognises the striker’s temperamental shortcomings, but remains certain that the 22-year-old will still fulfil his potential after working particularly hard in training this year.
Speaking to the Manchester Evening News, Toure said: "Mario is an unbelievable player, but sometimes he can be angry with himself.
"All players need to improve, and I talk all the time with Mario. This year especially he has been working hard in training, and improving well, but sometimes in the game you can get so disappointed when you lose small things.
"But he has fantastic character, and I know he will be one of the top strikers in the Premier League."