Jayden Bogle scored the controversial winning goal as Sheffield United came from 1-0 down to beat Birmingham 2-1 and continue their quiet climb up the Championship table.
A second goal in as many games for Blues new boy Lyle Taylor gave the hosts the lead (61), but Billy Sharp - who turns 36 on Saturday - finished from close-range to restore parity within seconds (64).
With 15 minutes to play, Bogle slotted in after an intricate build-up from the Blades, but Birmingham boss Lee Bowyer was left seething on the touchline after Sharp's run offside in the build-up had not been spotted by the officials.
As a result of their third straight win, Sheffield United move up to 10th, three points off the play-off places, but with up to three games in hand over their direct competitors. Birmingham stay 17th.
Admirable turnaround sees Blades win again
As had been the case for the past two home games, Birmingham fans once again took the opportunity to illustrate their dissatisfaction transparency and visibility of the club's ownership.
A pre-match statement had called for calm ahead of planned demonstrations, with sections of the home crowd staging a 'faceless' protest by wearing white masks and then, after kick off, simultaneously blowing whistles. It did eventually subside without causing disruption to the match, as had been the fear.
The majority of the first half - which ended without a shot on target from either side - passed without incident, though after 14 minutes, Sheffield United were denied a penalty by referee Keith Stroud when Iliman Ndiaye went down after seizing on a breakdown in communication and darting into the box.
Ndiaye appeared to lose his balance after Blues defender Teden Mengi had crossed his path from behind, before momentum sent him to ground. Referee Keith Stroud, however, was left unmoved.
Just after the hour, Birmingham were denied a spot-kick of their own when Bogle appeared to handle a cross, but moments later they had the lead anyway, when Taylor - who had scored on his debut against Derby on Sunday - controlled a pass from Juninho Bacuna and coolly slotted into the bottom right corner.
Had Bacuna not fired straight at Wes Foderingham moments later, the Blues could have been 2-0 up and cruising. Instead all-time record Championship scorer Sharp increased his record haul to 123 goals when he made a great run into the box and stroked Sander Berge's inch-perfect ball home.
Then came the turning point in the game. Sharp appeared to stray offside as a long ball was pumped forward, with Neil Etheridge forced to race from his line to head clear. No flag was raised, though, with the visitors allowed to continue to build an attack.
And after quick interplay in the box, Bogle was on hand to nip into the box, take an exquisite first touch and poke through Wes Foderingham's legs to seal all three points.
Man of the match - Billy Sharp
Sky Sports' Andy Hinchcliffe on Sky Sports Football:
"His goal turned the game, but his all-round performance was outstanding. He also showed his aggression and leadership, playing his part in what could be a massive three points for his club."
Analysis: Should Bogle's winner have counted?
Jobi McAnuff on Sky Sports Football:
"That's the bit I don't get [the fact that Sharp supposedly was not interfering with play]. If Lee Bowyer has been told that, then I get his grievance and frustration because he is clearly interfering with play, bearing down on the goalkeeper. That's the reason Neil Etheridge heads the ball.
"It is a really tough place to be when you have just lost a game after a contentious decision and you are being told something by the referee that you don't necessarily agree with.
Karen Carney on Sky Sports Football:
"He was offside - it's clear. I completely agree with Lee Bowyer that Sharp was in an offside position. The referee and the official on the side didn't see it, for whatever reason, and the phase continued.
"Unfortunately for Birmingham, the rest happens and they could have defended it better, but I felt he was in an offside position and it wasn't given. But you can defend these phases better."
What the managers said...
Birmingham's Lee Bowyer: "Yet again decisions are going against us, big decisions. I can't tell you how many apologies I've had this season for wrong decisions. If someone can tell me that the rules have changed, then that's fine. The rules are, if he is interfering, he's offside. If he isn't there, closing down my goalkeeper, then my goalkeeper brings it down and clears it normally. He can't do that because of the pressure he is being put under.
"The second goal on Sunday [against Derby] was the same. It was offside, but it went against us again. It can't keep happening. I'm sick of the apologies. I saw the linesman running along the line and he wanted to put his flag up, but then he said Sharp wasn't close enough to the goalkeeper. He was sprinting at him! So if you know that he's offside, it doesn't matter how close he is, he's sprinting and now making the goalkeeper's decision. If he wasn't there, the goalkeeper would've backed off and caught it in his own box.
"I feel for my players, my team and the fans that spend their hard-earned money to come and support the team and, again, we've been robbed of something we deserved."
Sheffield United's Paul Heckingbottom: "I'm delighted with the three points and delighted with the character that was shown. We were good in the first half but we spoke about being just that little bit better without the ball in terms of intensity and a bit more aggression and with the ball, with the quality of the final pass. In the second half, we were much better in both departments.
"We're taking it a game at a time. I know it's cliche, but we've got that many that we can't look further ahead than West Brom on Wednesday and, two-and-a-half days later, Huddersfield away. But we're pleased with where we are and we're pleased to be playing the teams around us."
What's next?
Both teams are back in action at 7.45pm on Wednesday February 9. Birmingham travel to the Vitality Stadium to face Bournemouth, while Sheffield United host West Brom at Bramall Lane. Both matches will be available to watch live on Sky Sports Football Red Button.