Bristol City interim Roy Hodgson suffered defeat in what is expected to be the final away game of his 50-year managerial career in the St Andrew's sunshine.
The former England boss watched his side lose 2-1 to first half goals from Phil Neumann and Jhon Solis as Tomi Horvat's late penalty turned out to be mere consolation.
The 78-year-old came up against a motivated Birmingham team looking to end their home campaign on a winning note and featuring three changes to the one which beat Preston in midweek, with Demarai Gray notably coming in for the injured Ibrahim Osman.
It took only eight minutes before the winger made an impact, taking a free-kick on the right and curling it into the box where he found Neumann unmarked.
Ten yards out the German produced a cushioned volley that flew past Radek Vitek and into the net for this third of the season.
Eleven minutes later Gray thought he had scored himself when, with another more centrally-positioned set-piece, he went for the near post and struck the outside.
Then four minutes after that the Jamaica international was first to react to Carlos Vicente's cross at the back post but his connection lacked the pace to beat Vitek.
The Robins' goalkeeper could do nothing about Solis' 29th minute goal though. Blues boss Chris Davies had been urging the Columbian to press higher all game and when he did he immediately forced a loose touch out of Sam Morsy.
Solis volleyed goalwards and referee Robert Jones' watch told him the ball had crossed the line.
The visitors reshuffled at half-time with Rob Dickie coming on for Cam Pring but it did nothing to disrupt Birmingham's attacking thrust.
Five minutes after the restart Kai Wagner's corner was cleared only as far as Vicente 20 yards out, where the Spaniard slashed a bouncing ball goalwards that needed tipping over.
Two minutes after that Jay Stansfield threaded a pass in behind the Robins' defence that put August Priske in on Vitek and as the goalkeeper came out he lifted it goalwards - only to see his chip curl on to the upright and bounce to safety.
Seconds later Gray sent over a left wing cross that Priske met cleanly with his left foot but the shot flashed narrowly wide.
The visitors were given hope in the 82nd minute when Stansfield slid in on Horvat on the left of the penalty area and conceded a spot-kick. The Slovenian picked himself up and sent James Beadle the wrong way from 12 yards.
Birmingham's Chris Davies:
"We've been excellent at home. We've been in the top three or four for home form.
"We've lost three games at home in the whole two seasons I've been here. If there's another team in England that's done that, I'd be surprised.
"It's a fortress because it's one of those grounds that people don't like coming to, the fans give us that extra edge.
"There's a great feeling here, a confidence, everything about the stadium, it's something pretty special we need to hang on to and the fans absolutely play their part.
"Of course we need to try and improve our away form, but the home form for me is always the most important thing for a team."
Bristol City's Roy Hodgson on his future as he refuses to rule out management return when Bristol City time ends:
"I've got to be very careful what I say now, I've made a bit of a fool of myself two or three times already, there's only so many gold watches you can get.
"Who knows? I've never been putting my CV out to clubs anyway. I've not had an agent ringing around trying to find me a job.
"I've just been fortunate, I suppose, that one or two jobs have found me, that I felt I'm able to do - and have broken a retirement promise to my wife and come back and taken them.
"I refuse really anymore to say 'right, this was great, I shall never even contemplate being in football in another role again'. That would be a mistake because I might.
"Some nice little national team might come and say 'come and join us for a little bit, work every now and again', I might enjoy that.
"I didn't expect this one, it was a real surprise when this came out but it was a pleasant surprise, it happens, and one that I'm glad that I took the opportunity."
