Villa striker Agbonlahor told PA Sport: "Liam has done well. I speak to him every week, keep in touch quite a lot and I'll have a word to try to find out some team news for Sunday.
"It was a good move for him. He wasn't getting the chances here at Villa so to play regular Premier League football, and to get the captain's armband, you can't ask for any more really.
"Was it a funny move by Liam? It was a bit of a dangerous move but he wanted to play football and fair play to him."
Agbonlahor will try to use his explosive pace to unhinge the Birmingham defence and add to his four league goals and exploit any weaknesses in Ridgewell's game.
He said: "I think everyone has got weaknesses but I don't want to talk about 'Ridge' in that way. He is a really good defender and we will have to wait and see what happens.
"He is a really good defender, good at leadership skills, a good choice for Steve Bruce."