Striker Balotelli was not involved on Sunday (NZST) as new boss Vieira suffered a losing start in Ligue 1, Nice going down 1-0 at home to newly promoted Reims.
Asked about the absence of the Italy international, Vieira confirmed the player had made clear his desire to move on after two seasons at the club, and therefore was not considered for selection.
"The player wants to leave, so it’s unlikely he’ll remain here," the former Arsenal midfielder said.
"We want players whose desire it is to go forward with the club. It’s a very complicated and difficult situation, so the club will try to do whatever is possible to help him leave."
Balotelli, who has scored 33 league goals since joining Nice after a disastrous spell with Liverpool, held talks over a move to domestic rival Marseille, only for negotiations to hit a stumbling block.
The 27-year-old has also been linked with a return to Serie A, albeit Napoli president Aurelio De Laurentiis emphatically dismissed the idea of signing the former Inter Milan and AC Milan forward last month.