Vieira gave Balotelli a late cameo in Sunday's win as a second-half substitute.
The Frenchman said: "(Alessandro) Zanoli on the right has done really well, Vitinha is coming back from an injury and we'll give him time.
"I think Zanoli and (Fabio) Miretti are working well defensively too, the substitutes have brought energy to the team.
"Balotelli played about fifteen minutes, he's worked well during the week and he has to continue like this. Mario, like Vitinha, must continue to work, I'm happy with him."