North of the border, they managed rival clubs in a city where a derby is almost a matter of life and death and now Villa and former Celtic manager Martin O'Neill is set to lock horns once again with his old adversary after former Rangers boss Alex McLeish left Scotland for Birmingham City.
Blues have announced a press conference for this morning when they are expected to unveil the 48-year-old as the man to replace Steve Bruce at St Andrew's.
McLeish handed in his resignation as Scotland coach yesterday after being refused permission by the Scottish FA to speak with the Blues' board following Bruce's departure to Wigan along with assistant Eric Black.
O'Neill, who faced McLeish in many Old Firm derbies over the years, believes Blues have made a great appointment if every-thing goes to plan today.
The Villa boss, Scottish Manager of the Year in 2002 and 2004 with Celtic - sandwiching McLeish who won the honour with Rangers in 2003 - said: "If Birmingham get Alex McLeish, and it looks as though they will, then they will be getting a very good manager - a very good manager indeed.
"He was at Rangers when I was at Celtic and he was a really, really fine manager. If Blues secure his services they will be doing very, very well indeed."
O'Neill and McLeish are hardly buddies but they have a mutual respect for each other built up over years managing the Scottish Premier League's two biggest sides in a city where football is everything.
If the expected happens today without a hitch and Messers Sullivan and Gold announce McLeish is the new Birmingham City manager, it sets up a thrilling Second City derby between the two managers at Villa Park in April.
O'Neill said: "I don't know Alex socially at all but over the years I have come to know him and respect him as a manager.
"In the first few Old Firm derbies he probably came out on top and won the games but then we started to win from then on. I think he is a really good manager and his record speaks for itself.
"It was tough being rivals but only as tough as life in football can be."
O'Neill watched the developments up in Scotland and in turn across the city unfold yesterday as first the Scottish FA announced McLeish would not be given permission to speak to Blues and then he resigned anyway.
The Villa manager continued: "He will be very good for Birmingham City I have no doubt. The Scottish FA will be disappointed as that is two really good managers they have had in Alex and in Walter Smith who have moved on.
"If Blues can secure the deal today then they should do it."