Gareth Barry struck deep into injury time to overcome a resilient Reading side and keep up pace with league leaders Manchester United.
City famously scored twice in stoppage time against QPR to clinch a dramatic maiden Premier League crown at the end of last season, and Mancini admitted he would rather his side were to seal victories earlier in the game.
He told reporters: "It’s more important to score early on in games - my heart is not strong for these late goals!
"I think that we deserved to win but when you are in the last two or three minutes it can be difficult if you don’t score in the first half when you have lots of chances.
|GOALS GALORE ON BOXING DAY?|
|10/1||Man City and Sunderland are 10/1 with PaddyPower to score six or more goals on Boxing Day|
Just three days after Mario Balotelli accepted a two-week salary fine from the club after receiving nine yellow cards, three red cards and a four-game ban for stamping on Scott Parker last season, the striker was absent from Saturday’s matchday squad.
However, Mancini assured that the Italian’s no-show was due to illness.
"Mario is ill. He came to the training ground yesterday because he wants to play but he can't."
The headline from the pre-match team news was the inclusion of 18-year-old debutant Karim Rekik following the absence of left-backs Gael Clichy and Aleksandar Kolarov, and Mancini hailed the defender’s display in a position that does not come naturally to him.
"Karim played well, he’s very young only 18 but he has good quality – he played very well," Roberto declared.
"He’s a central defender but he can play left-back – we are very happy with him."