Manchester United striker Rooney struggled to make an impact over the course of the game.
Mancini declared: "Comparing Balotelli's performance with Rooney, Mario was much better. He is an excellent striker and we must continue to support him.
"Some people underestimate perhaps Balotelli, but he is always in the heart of the game. He had five or six scoring chances last night and he was unlucky not to score."