Matt Smith and Danny Pugh scored second-half goals as Leeds inflicted a 3-1 defeat on strugglers Birmingham, who slipped into the bottom three of the Sky Bet Championship for the first time this season.
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It was the 17th successive home game in which Birmingham have failed to win and highlights their current desperate position.
The Blues played with plenty of commitment until a tragic two-minute spell when Smith and Pugh displayed superb finishing.
Their tale of woe was completed when Paul Caddis turned a Ross McCormack cross past his own goalkeeper in the 78th minute.
Substitute Federico Macheda popped up with an 83rd-minute goal but it was only a consolation effort.
Leeds' win was their third in four games and they have all come against struggling teams - Blackpool and Barnsley - in the bottom four.
In the process, they completed the double over crisis club Birmingham following a 4-0 success at Elland Road.
In such a crucial game, Birmingham adopted an attacking policy at the outset and it very nearly worked. However, they ran out and steam and were destroyed by Leeds' fine finishing.
Early on it had looked promising. Lee Novak had one attempt just off target but the best opportunity fell to young Tom Adeyemi in the seventh minute.
He cleverly flicked Novak's waist-high pass forward and in the process created a clear opening, but with only former Birmingham goalkeeper Jack Buckland to beat, Adeyemi carelessly floated his shot high over the bar.
Leeds finishing was hardly any better at this stage. Leading marksman, McCormack, was kept relatively quiet and it fell to Michael Tongue to attempt to give the visitors an early advantage, but his finishing also left a lot to be desired.
At this stage Leeds' defence appeared far from confident and Birmingham's determination was clearly a feature of the proceedings.
There was some frantic play and it only briefly abated when Jason Pearce was booked for a reckless tackle on the bustling Nikola Zigic.
Leeds weathered the storm and they created a smart opening for Tongue but the former Stoke player's shot was blocked by goalkeeper Darren Randolph as the first half petered out goalless.
Birmingham continued to strive for the vital goal, but clear-cut chances never materialised despite some good attacking play by stand-in skipper Chris Burke.
In their quest to score, Birmingham left themselves exposed and Leeds took full advantage with two goals in two minutes from Smith and Pugh to completely demoralise the home side.
The turning point of the game occurred in the 58th minute when Smith rose high to head home a Tongue cross.
His goal deflated Birmingham and before they had time to recover their composure they were two goals in arrears, when Pugh drilled a low shot into the corner of the net cutting in from the left.
To add to Birmingham's disappointment Caddis then scored an own goal when he turned in McCormack's short cross.
Substitute Macheda pulled back a goal with a powerful left-footed shot seven minutes from time but the damage had already been done.