Ferguson, often regarded as a mentor for McLeish having given him his break as a player at Aberdeen, is convinced his fellow Scot will prove doubters wrong.
The 70-year-old said: "At the end of the day what will count is this - can he do the job for Villa?
"It doesn't matter whether there are 50 against him, 500 against him or five against him because the experience and the ability he has got, believe me, he will prove that he can do the job.
"I've known him for a long time and I know his abilities. I know how conscientious he is. I know the determination and work ethic he's always had to make sure he does the job right."