Fergie believes Mark Hughes’ side will find it tough to win the Premier League title.
City signed players such as Emmanuel Adebayor, Kolo Toure and Carlos Tevez for big fees this summer.
“The rivalry has gone up a notch in the last few months, with them signing all those players and then coming up with that advert and all their posters about Carlos Tevez,” Ferguson told American radio station Sirius XM.
“They’ve been a bit, how can I put it, cocky. Yes, a bit cocky. They’ve got seven centre-forwards now, which is crazy, just amazing.
“But when you have spent that amount of money, and the wages they are paying, you have to win the league with that kind of investment. That’s where the difficulty will come for them.
“It’s going to be very difficult for them to win the league when you see ourselves, Liverpool, Chelsea and Arsenal because they’ve got to beat the four of us at some point to get the league.
“It’s very difficult to get into the top four and it’s even more difficult to get into the top one – and that’s what this league is all about, being No.1.”