The game exploded in the 52nd minute when Dion Dublin was sent off. The Villa striker conceded a free kick with a sliding tackle on Robbie Savage who was upended.
Savage was far from pleased to receive treatment he often dispenses. Both Dublin and Savage exchanged words face to face only a couple of yards away from the referee.
Suddenly Dublin head-butted Savage and referee Mark Halsey had no alternative but to red card the Villa striker who had only returned to the team following a one-match suspension.
The incident could have become even worse as other players suddenly became involved but Halsey defused the situation and the outcome was that Savage uncharacteristically became subdued.
Savage had been in the thick of the action in a hectic start when both teams were guilty of some rash tackling. The former Leicester star, one booking short of an automatic three-match ban, was quickly brought to book by Halsey following two reckless lunges which could easily have earned a yellow card.
Lee Hendrie, one of four changes in the Villa side from that defeated at Charlton, wasted a good opportunity after being set up by Dublin.
Goalkeeper Peter Enckelman came in for some heavy heckling from the Birmingham fans after his tragic own goal in the game at St Andrews earlier in the season.
But Birmingham failed to test Enckelman or put him under any pressure as Villa dominated the first half.
Enckelman, however, demonstrated his ability when Christophe Dugarry managed to fire the first shot of the game on target five minutes before the break. The Villa keeper responded by flipping the shot over the bar.
Stan Lazaridis was not so conspicuous as in recent games. Although he linked up on a couple of occasions with Dugarry the Australian international was generally kept in tight check by J Lloyd Samuel.
The second half continued to be an untidy affair and the sending off of Dublin helped to maintain an uneasy air to the proceedings.
In such a keenly-fought affair which produced 28 fouls in the first hour, the game turned in Birmingham's favour when Lazaridis headed home a right-wing cross from Jeff Kenna in the 74th minute for only his fifth goal in four seasons at Birmingham.
Enckelman then failed to reach a back pass from Samuel and Geoff Horsfield nipped in to grab the second goal three minutes later to put the game out of Villa's reach.
To add to Villa's woes Joey Gudjonsson was sent off with ten minutes left.
The Icelandic midfielder was shown a second yellow card for a foul on Matthew Upson. He had been booked just five minutes earlier for bringing down Dugarry.