Tevez has returned to the City starting line-up in their past three matches, and his four goals in these appearances have seen Mancini's men move back into contention following their mid-season slump. City now lie three points behind United, but Mancini refuses to concede that Tevez's six-month absence after their infamous falling out in Munich last September has played a part in the title race.
"No, I don't think this," said Mancini. "It was a strange situation six months ago and I said to Carlo, a lot of times, apologise and it would be finished. Carlos didn't want to do this, he wanted to leave the club in December.
"But if we are here it is also because the other players were playing very well. (Sergio) Aguero scored a lot of goals, (Edin) Dzeko the same, (Mario) Balotelli, all the team played well. If not, it is impossible we would be here at this moment."
Tevez, who has also made four substitute appearances since returning from his unauthorised sojourn to Argentina, is yet to complete 90 minutes despite making such an impact.
"Carlos is not 100%, because it is impossible for him to be 100% after six months without playing," Mancini said. "But he has experience, he is a clever player. He has scored four or five goals and this is important.
"It is difficult for him to play after six months. For this reason he played only the last two or three games. I think he can find his best form next season, after pre-season."
When asked if that meant Mancini wanted to keep Tevez, who is widely expected to leave in the summer, the Italian was coy.
He said: "I think he has a contract with Manchester City, but I don't think in this moment it is important to talk about the future for everyone."
Meanwhile, City's other controversial striker Mario Balotelli is hoping to force his way back into the action after missing the last three games through suspension.
With that merely being the latest in a long line of misdemeanours, the 21-year-old's future at the club was thrown into doubt. But Mancini has not ruled out recalling his fellow Italian for Monday's crunch clash, which could see City return to the top with two games remaining with victory.
"Mario is a player like the other players. He is available for Monday and after we decide," Mancini said.
"In one game Mario can do everything. He can score two or three goals if he decides this. This is the manager's problem."
Mancini has previously said he cannot trust Balotelli but thinks he could in such a big game, saying: "I think in this game yes - only in this game!"