Match ends, Birmingham City 1, Leeds United 2.
Birmingham City's slim Championship play-off hopes faded even further as a goal in each half from Stuart Dallas earned Leeds United victory.
He fired in from the edge of the box on 11 minutes before doing the same from slightly further out with another low, right-foot shot on 53 minutes.
Blues top scorer Clayton Donaldson pulled a goal back three minutes later.
But that was all they could manage against a side reduced to 10 men in injury time when Alex Mowatt saw red.
Birmingham, who remain nine points adrift of sixth-placed Sheffield Wednesday, had failed to win in five games prior to Saturday's victory at Reading.
That weekend win had suddenly rekindled play-off hopes and Blues began the night knowing that they had the chance to reduce the gap to six points.
Their task was made a whole lot harder when Dallas fired the first of his two goals into the bottom left corner.
But his second proved the killer blow, despite the home side pulling one back within three minutes.
Donaldson hooked home his ninth goal of the season after Leeds keeper Marco Silvestri did well to keep out David Cotterill's powerful shot.
That gave Blues more than half an hour to level but substitute Diego Fabbrini's wild shot over the bar from six yards was the closest they came to an equaliser.
Mowatt's red card for a late tackle on Ryan Shotton came too late to matter, as Blues slumped to only a second home defeat in 12 games.
Birmingham manager Gary Rowett: "There was a little chance (of the play-offs) but the main emphasis was for us to win games - particularly this one as it was our game in hand.
"The first half was poor and as disjointed on the ball as we have looked all season. In the second half we livened up and we started to play the way I know we can and we dominated the whole half.
"When we are at it we are a match for everyone. If we drop away by 5-10%, we are just ok."
Leeds head coach Steve Evans: "We will appeal the sending-off. He slid in with his feet on the floor and it is a yellow card at best.
"But I would prefer to concentrate more on our performance which was very, very good.
"All the offensive players in the first half caused problems. The disappointing thing was that it was only 1-0 at half-time and not more."
- 8GleesonSubstituted forToralat 61'minutes
- 11CotterillSubstituted forFabbriniat 76'minutes
- 25LaffertyBooked at 89mins
- 28BerardiBooked at 32mins
- 3BambaBooked at 90mins
- 15DallasSubstituted forCarayolat 83'minutes
- 8MurphySubstituted forBellusciat 88'minutes
- 23L Cook
- 7AntenucciSubstituted forMowattat 69'minutesBooked at 90mins
- Chris Kavanagh
- Shots on Target
Second Half ends, Birmingham City 1, Leeds United 2.
Alex Mowatt (Leeds United) is shown the red card.
Ryan Shotton (Birmingham City) wins a free kick on the right wing.
Foul by Alex Mowatt (Leeds United).
Hand ball by Maikel Kieftenbeld (Birmingham City).
Attempt saved. Clayton Donaldson (Birmingham City) right footed shot from the right side of the box is saved in the bottom right corner. Assisted by Jon-Miquel Toral with a through ball.
Attempt missed. Kyle Lafferty (Birmingham City) right footed shot from outside the box is too high from a direct free kick.
Sol Bamba (Leeds United) is shown the yellow card for a bad foul.
Clayton Donaldson (Birmingham City) wins a free kick in the attacking half.
Foul by Sol Bamba (Leeds United).
Kyle Lafferty (Birmingham City) is shown the yellow card for a bad foul.
Foul by Kyle Lafferty (Birmingham City).
Mustapha Carayol (Leeds United) wins a free kick in the defensive half.
Diego Fabbrini (Birmingham City) wins a free kick in the attacking half.
Foul by Giuseppe Bellusci (Leeds United).
Substitution, Leeds United. Giuseppe Bellusci replaces Luke Murphy.
Corner, Birmingham City. Conceded by Charlie Taylor.
Substitution, Leeds United. Mustapha Carayol replaces Stuart Dallas because of an injury.
Delay over. They are ready to continue.