The Italian claimed the Serie A title three times as Inter Milan boss and twice as a player when at Sampdoria and Lazio.
However, the 47-year-old insists winning in England would be special because he regards it as the best league in Europe.
“If we beat United to the title it would be the biggest achievement of my career,” Mancini told reporters.
“That’s because it’s in England, it’s the best championship in Europe. For an Italian manager to win the Premier League would make it better than anything else I have done in the game.”
|MAN ON A MISSION
|7/4||Manchester City are 7/4 with Paddy Power to win the Premier League title this season.|
Mancini feels a title triumph will have huge significance for City after going so long without winning the league and he now wants to create a dynasty of success at the club.
“Winning trophies is important everywhere, whether it is Barcelona, Real Madrid or Manchester City,” he added.
“But when you win with a club like City you change history as well and that would give me a greater sense of satisfaction.
“For over 40 years they haven’t won the league, so if we can do it, it will be better than at a club that’s used to winning titles. One of the things that attracted me to City was the chance to change their history. This has always been the way in my football life – I like a challenge.
“Some managers go to a club that’s already set up to win because it has top players. For me it’s different. I’ve always gone to clubs who haven’t won anything for a long time.
“It’s important that we don’t win just one championship. I want to leave a legacy. I want all the City supporters to remember me for winning many trophies and because I’ve worked well here.”
The Italian feels Monday’s vital derby clash is the most important game he has been involved with since a European Cup final meeting with Barcelona as a player in 1992.
On that occasion Mancini was on the losing side but he has vowed to not let that happen this time around.
“I feel the same sense of importance about Monday as I did as a player for that game,” said Mancini.
"It was so important for Sampdoria. It was the first and last time the club has ever reached the European Cup final.
“We were unlucky in that game but Monday is just as important, because City last won the last title in 1968. Our supporters deserve to win the title after such a long time and we want to do it for them.”