Nasri, 24, has been handsomely reward following his £22m move but Mancini is adamant the France international - whom he said he tried to sign from Marseille five years ago when he was Inter Milan manager - has joined City for all the right reasons.
"He wants to make history for this club," said Mancini, who is "delighted" with City's Champions League draw. "When I was playing, it was important to help make history. It is good to play for (clubs like) Real Madrid, Barcelona and Manchester United.
"But if you win with a team that never wins - like Sampdoria and Lazio - it's better. If we can do this here, it will be very important. We want to improve on last year. We have a big chance this year; everything depends on us."