Leeds claimed a league double over Cardiff to damage the Bluebirds’ hopes of reaching the Championship play-offs.
Leeds withstood heavy Cardiff pressure before taking the lead as Souleymane Doukara scored with a deflected shot.
Despite having Fabio sent off after an hour, the hosts continued to dominate as Lex Immers hit the post and Kenneth Zohore headed against the bar.
But Leeds’ Mirco Antenucci struck on the break in added time as the Bluebirds dropped to eighth.
Leeds, meanwhile, move up to 15th after securing a first league double over Cardiff since 1984.
The loss is a setback for Cardiff who, buoyed by their first back-to-back wins since September, had started the match with their sights on the play-off places.
But a first defeat in 14 home matches leaves them two points behind the top six.
Peter Whittingham’s whipped free-kick and Tom Lawrence’s stinging low effort were both saved by Marco Silvestri as the hosts made a confident start.
But it was Leeds who struck first, taking the lead against the run of play.
Antenucci led the visitors’ counter attack, scampering clear and squaring the ball to Doukara, whose shot hit Fabio on its way in.
Cardiff continued to press with chances for Immers and Anthony Pilkington, but Silvestri preserved the visitors’ lead at the interval.
Leeds could have doubled their lead early in the second half, but Antenucci had a shot blocked on the line by Bruno Ecuele Manga and two others saved by David Marshall in quick succession.
From that point onwards, it was sustained Cardiff pressure once more as Immers had one effort saved while another hit a post.
Their attempts to salvage a point were undermined by Fabio’s dismissal for two yellow cards in seven minutes, but still they created chances, with Zohore heading one against the bar and another narrowly over.
Cardiff City boss Russell Slade: “Sometimes the game is cruel. We were knocking on the door all evening and even dominated with 10 men.
“I’m disappointed with the two goals, especially the first which we should have dealt with comfortably had we been more aware.
“But apart from those two lapses in concentration, the attitude was first class. Their goalkeeper was inspired and we didn’t have that ruthlessness to score and get the victory we deserved.
“We had a stonewall penalty (for an alleged handball by Giuseppe Bellusci). The player’s arms were out and if that’s not a penalty then I don’t know what the rules are. We gave a performance but didn’t get the result.”
Leeds united manager Steve Evans: “The players deserve all the credit for that win. We learned some harsh lessons in the defeat to Brighton but I feel we’ve been in a good place since then.
“Cardiff’s goalkeeper [David Marshall] could have been named man of the match in the first half with some fine saves before half-time and had we got that second goal then we would have won comfortably.
“But people will forget those saves because of Silvestri pulled so many out of the bag in the second half.
“It helps when you have two centre-backs playing so well and the defence working together like that, while you have two strikers who just ran all night.”