Balotelli had a chequered career at Inter before joining City for £23million in the summer, falling out with former coach Jose Mourinho and several team-mates over his attitude to training and work-rate in games.
Backing: Manchester City's Mario Balotelli
Vieira warned the 20-year-old that he still needs to work harder for the team, but is in no doubt about Balotelli's potential after seeing the youngster score twice against Salzburg on Wednesday to take his total to five goals in four starts for City.
Vieira said: 'Yes, there's no doubt he can become one of the best strikers in the world. The potential and the quality are there. Of course Mario made mistakes when he was at Inter and he has to learn from that and improve. That's the important thing, and he's on the right track.
'He's young and he's determined to learn. He just has to get his focus on the game.
'He's a class striker, a natural finisher who scores goals for fun. He's somebody who you know will shoot 10 times, hit the target maybe nine times, and score eight goals.
'But sometimes it is not enough to make a career. If he wants to be one of the top strikers in the world, he needs to work harder than he is doing at the moment.
'The Premier League is more demanding to work without the ball. He needs to work hard and if he does, he will be one of the big surprises in the Premier League.'
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