Having seen off the threat from, among others, Kenny Dalglish, Arsene Wenger and Jose Mourinho over a quarter of a century in charge of Manchester United, McLeish believes Ferguson will want to hang around long enough to put City manager Roberto Mancini in his place - especially after last month's derby humiliation.
"That has got Sir Alex going again. Mancini has thrown down the gauntlet and he'll be rearing up at that one. Absolutely. No danger that he will want to put that right.
"He sees City as a genuine threat and I think they are the real deal. Mancini is Sir Alex's challenge now, he'll want to see him off like all the others.
"If he had not been so successful you could understand that mentality in a way, because he would still be striving for that success.
"He has seen a million managers come and go - his adversaries - and it's almost like when he sees a new manager talking a good game, he has got to hang around and see him off as well."