City's win over Wolverhampton Wanderers, coupled with United's 4-4 draw with Everton, has left the Citizens just three points behind the Red Devils going into what Sir Alex Ferguson has described as "the most important" Manchester derby in his time at the club on Sunday.
But despite coming back from a poor string of results, Mancini still insists that United will win the Premier League.
"Only one team can win this title," Mancini said.
"I've never bet in my life but if you were to ask I would say put your money on United, 100 percent.
"I don't have a message for Sir Alex. If I did it would only be 'Congratulations for your season and for this title'!"
After Sunday's derby, City face Newcastle United and Queens Park Rangers, while United play Swansea City and Sunderland.