The Eastlands outfit climbed to the top of the Premier League on goal difference with their 1-0 victory over the Red Devils this week.
And if the Citizens win their last two games of the season against Newcastle and QPR it would almost certainly ensure that they would lift the trophy.
But Ferguson believes their rivals should exercise caution at St James’ Park on Sunday because they will be facing a team on the up after beating Chelsea 2-0.
"The challenge for City is to win at Newcastle," said the Scot.
"Newcastle is a very difficult place and they are playing well. After that incredible defeat at Wigan, they galvanised themselves to win at Chelsea and, as everyone knows, winning at Chelsea is very difficult. We have not done it for eight years."
And he added that for Manchester United to win the Premier League title they would need Manchester City to drop points due to the disparity in goal difference between the two sides.
"They have got two games left. If they win their two games they win the league,” he added.
"People talk about goal difference, but it depends how many they win by. Say they win 3-0 on Sunday, their lead would be 11 and they still have QPR at home. That would be impossible."