Mancini, who has repeatedly played down City's hopes of being crowned champions of England for the first time in 44 years, saw his men move to within three points of United with a 2-0 win away to Wolves on Sunday.
Goals from Sergio Aguero and Samir Nasri meant City, whose win relegated Wolves, could now go top on goal difference with two matches then remaining if they beat United at Eastlands next Monday after the champions were held to a shock 4-4 draw by Everton at Old Trafford earlier Sunday.
"We will talk about one team winning the title on Monday night (April 30) if we beat them," said Mancini.
"I probably expect us to lose to Manchester United. Their players are used to playing under pressure every year. But we don't have any pressure as we have no chance of winning."
Most observers believe Mancini is merely trying to lift the pressure off City and trying to deflect it onto Sir Alex Ferguson's men by insisting United have already won a 20th English title.
But whether Mancini really believes what he's saying or not, he is sticking to his guns all the same.
"I'm standing by what I said," Mancini insisted. "We are still three points behind. I'm smiling because we can finish well this season.
"We've won three (successive) games and now we have a derby. We want to play well for our supporters," added Mancini, whose side were eight points adrift of United just a few weeks ago.
"I don't think we played as well as we did against Norwich and West Brom," conceded Mancini. "We only played so-so."
"Congratulations to Sir Alex for his season and his title!"
Terry Connor, the Wolves manager, broke down at the post-match press conference after the realisation of relegation set in.
"They've been doing that for quite a while now," said a tearful Connor. "They gave everything they've got to give but after 35 games we found it too difficult.
"It's emotional and very raw for the staff, players and supporters for the club. I'll find the next few days really tough.
"We'll be honest and competitive for three more games. We owe it to everyone to finish it off well."
Former Wolves assistant manager Connor refused to confirm whether he'll be at the club to turn things around next term, having failed to win a single game since succeeding the sacked Mick McCarthy in February.
"It's too soon to plan for next season but we'll sit down with the club at the end of the season," he said.
"I've been here 13 years and I cannot put it into words. It's a real raw, emotional, tough day for everyone.
"Wolves is a club with a lot of tradition, has had some good times and successes. This season will be seen as one of the least successful ones but we'll bounce back, whoever's in charge.
"The fans gave us every backing. For them it will be really tough. It's their club and they must keep supporting the club."