Birmingham leapfrogged West Brom into fifth in the Championship table after coming from a goal down to win the West Midlands derby 3-1 on Friday night.
John Swift's sixth goal of the season put the Baggies in front after six minutes, but the Blues levelled through Juninho Bacuna's penalty, which was controversially awarded after Cedric Kipre and Koji Miyoshi both slipped as they challenged for the ball.
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Dion Sanderson looped in a header to turn the game in the hosts' favour before the break, before Gary Gardner curled in a stunner of a free-kick late on, within five minutes of being introduced.
The Blues climb from 12th up to fifth as a result of their second win in succession, with West Brom dropping down to seventh.
Derby night delight for the Blues
With West Brom unbeaten in five and with just one defeat to their name since the opening day, it perhaps did not come as a huge surprise when they struck first after just six minutes.
A Birmingham clearance did not reach its intended target, which allowed Grady Diangana to seize control of the ball and square for Swift, who passed into the net via the inside of the right-hand post.
The Blues were struggling to get into a rhythm after shipping so early on, but when referee James Linington pointed to the spot after the aforementioned incident between Miyoshi and Kipre, Bacuna's cool, composed finish gave them the stroke of luck they needed.
Seven minutes before half-time, they turned the game on its head. A shot from Bacuna was deflected behind, with the subsequent corner kept alive long enough to be worked to Cody Drameh on the right, whose cross to the far post was looped over Alex Palmer by Sanderson.
Just before the hour, Darnell Furlong had the chance to set up a grandstand finish when he ghosted into the box and met Matt Phillips' cross, but he slid the ball agonisingly wide. And the Baggies' night only got worse from there.
Swift departed, clutching his right calf, with 15 minutes of the 90 to play and, before long, it was game over, when Gardner bent a beauty of a free-kick over the wall and into the top left corner to earn a fourth straight derby win for Birmingham.
Eustace: A special night for Birmingham
Birmingham City manager John Eustace:
"I enjoyed the result. There were a lot of emotions throughout the game and I was ever so proud of the efforts of the boys tonight. They were fantastic. I think that's the first time we've come back from a goal down at home for a couple of years.
"The boys are showing great character at the moment, great attitude, everything we want them to do. We've got a very solid, professional group in there, with no egos. Everyone wants to do well for each other. It was a special night."
Corberan 'angry and upset' over penalty decision
West Brom's Carlos Corberan:
"It's difficult for me to have a good view of the game. We started really well and it's true that, in some moments, we didn't manage the game well enough in the attacking half. But I think it is obvious the penalty has changed the game, unfortunately.
"It was one action that impacted the game a lot. I didn't think it was a penalty live; immediately I watched the TVs and it was not a penalty. The more times you watch, the more angry and upset you can be."
What's next?
Both teams are back in action after the October international break.
On Saturday October 21 at 3pm, Birmingham travel to the Riverside to take on Middlesbrough, while West Brom host Plymouth at The Hawthorns.