Balotelli produced a typically unpredictable performance at Eastlands, scoring a brilliant goal, suffering an injury, getting booked and acting as peacemaker in a 3-0 win that earned the Blues a quarter-final meeting with Reading on March 13.
It means the Italian now has 10 goals from his 18 City games, eight bookings and a red card, but Mancini is happy he took the responsibility.
"I took a risk to play only Mario up front," said Mancini, who axed both Carlos Tevez and Edin Dzeko. "But Mario played well and scored a fantastic goal.
"I was very pleased with the overall performance. This game was very important for us."