Vieira played with Ibrahimovic at Inter Milan.
"I think he's one of the best buys in French football over the past 30 years. Zlatan is one of the best, Zlatan is a guy that makes a difference, who ensures that you win or lose a trophy," said Vieira.
"He will be the one who scores between 25 and 30 goals. One needs only look at what he has achieved so far. I think he's won nine (league) titles in the last ten years. What I really like about Zlatan is that he is not on the pitch to play around: he's there because he wants to win. He is a winner."