Foster was signed from Manchester United by McLeish when Birmingham manager during the summer of 2010 and helped them to lift the Carling Cup.
He was surprised to see McLeish move across the city to Villa Park but is backing him to deliver success.
Foster said: "I was surprised with the way it (McLeish's move to Villa) came about but I wasn't surprised in a way because I know Alex and the way he works.
"Alex McLeish is a great manager who will get the best out of the players he's got to work with.
"He did the best with the Birmingham squad in the last two years and taking them to a major trophy isn't something many people get to experience.
"If you look at Arsenal I'm not sure how many years it's been for them and then you've got a team like Blues doing it, which is a fantastic achievement.
"I know he'll get the best out of the squad he's got to work with. His training sessions are very good and, come matchdays, he does very good talks before the games. He motivates you very well.
"I knew his move was going to be a sore point for a bit but I'd like to think he'll win the fans around and he should be a success there as well."
Foster was unbeaten in three meetings with Villa last season and expects to be the target of the boo boys given his Blues connection.
He said: "I will get some (boos) to be fair but I'm used to that.
"We played each other three times last season and I was never on the losing side and hopefully I won't be come next week.
"We know it is going to be a tough match against Villa. They are coming off the back of a disappointing defeat against Man City and we are boosted by the big derby win against Wolves.
"We will go into the game full of confidence and if we get three points there, all of a sudden, it's a different story and we are in the top half of the table."
Source: Team Talk