Yaya Toure's two goals at St James' Park here on Sunday left visitors City top of the table heading into the final round of matches on May 13.
City, who haven't lost at home in the league all season, will now welcome strugglers QPR. And they go into the match with a plus-eight goal difference advantage over second-placed champions Manchester United.
Assuming City beat QPR, United would have to win by a huge margin away to Sunderland to deny their cross-town rivals a first English title since 1968.
But while United manager Sir Alex Ferguson suggested City had "two hands" on the trophy Mancini, who wrote off his team's chances when they were eight points adrift of United a month ago, would only say: "Maybe we are the favourites now.
"But, in one game, things can change," the Italian added. "We should keep our concentration like we have done the last five weeks
"I'm excited because we are top, but it's not enough. If we play like we did here I think we have a fantastic chance to be champions."
He added: We've still got a difficult game against QPR on the last day.
"At least it doesn't depend on Manchester United anymore, it depends on us, but we have another game.
"It won't be easy because QPR are fighting against relegation. If we think we have won the Championship it will be a big mistake.
"All the players have to keep their feet on the floor. I cannot talk about what it would mean to win the title, not until next week."
Toure, who was freed to move forward and score his goals after Nigel de Jong went on as a substitute, is also not as convinced as Ferguson that the race is run. "Only one hand on the trophy," was his verdict.
The Ivory Coast international added: "I always thought I came to this club to make a story. We are not there yet at the moment but it's important to keep going and try to help our team-mates."
Mancini paid tribute to Toure's influence on this victory by saying: "He is a fantastic player. He has experience of winning trophies at Barcelona and he has brought that to us.
"We brought him for that reason. He can play in a number of different positions, which is very important to us."
Meanwhile Newcastle manager Alan Pardew is now convinced City will be crowned champions. "The QPR game is one you would expect them to win," he said. "If I'm honest, City are the best team we have faced this season."
This defeat damaged Newcastle's chance of figuring in the Champions League next season, but they can finish in the top four if they win at Everton this coming Sunday and Tottenham and Arsenal slip up.
"It's a simple equation -- we have to win at Everton, but it may not be enough," said Pardew.
Despite the defeat, north-east giants Newcastle's fans stayed behind for a lap of honour from players, who held out for more than an hour and were sensing a victory before Toure struck his first goal in the 70th minute before adding a second late on.
"It was a terrific game," Pardew said. "You could sense it was real tight, tense affair and we had done our homework on each other. We stopped each other doing what we do well.
"One goal was going to change the face of the game. It needed a bit of quality to do that and Yaya came up with it.
"When the game opened up after the first goal, City looked at their best, but we kept them quiet until then."