Mancini publicly declared the title race over after City crashed to a damaging defeat at Arsenal last month, a result which left them eight points behind Manchester United.
But City clawed back that deficit in the space of their next four games, including a derby victory over United at the Etihad Stadium.
They now head into Sunday's final fixture against QPR leading the table from United on goal difference and, looking back, Mancini feels the Emirates Stadium reverse was a blessing in disguise.
The Italian said: "In the moment it was good for us, it took off all our pressure.
"For two or three games we played completely free.
"We believed we could play a derby three or two points behind.
"We believed always, also when we were eight points behind."
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Barring an unlikely landslide win for United at Sunderland, City know victory over QPR at home will guarantee their first title since 1968.
Mancini feels that is a success his side would deserve for playing the best football in the country this season.
Mancini's title destiny will be settled in a contest with his predecessor Mark Hughes, the QPR boss who was sacked by City in December 2009.
The match is also a critical one for Hughes, whose side need a point to guarantee avoiding relegation.
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