Nine-man Cardiff held on to deal Leeds United's survival hopes a massive blow at Ninian Park with Michael Chopra's free-kick on the stroke of half-time proving decisive.
Dave Jones' promotion-chasers are now firmly back in the hunt for a top-six finish after securing their fourth win from their last five Coca-Cola Championship matches, while Leeds' hopes of back-to-back league wins in their fight against the drop were dashed.
Leeds did not deserve to go behind at the interval when Chopra lashed home his 19th goal of the season from a 20-yard free-kick following Ian Westlake's foul on former Leeds player Simon Walton.
But after having match-winner Chopra and Walton harshly sent off in the second half, both for second yellow cards, Cardiff survived a frantic finish to deny Leeds a point.
Both sides made just one change with Kevin McNaughton standing in for the suspended Glenn Loovens in the Cardiff defence and on-loan full-back Armando Sa replacing Frazer Richardson for Leeds.
Robbie Blake and Chopra traded early shots with Leeds' Danish goalkeeper Casper Ankergren holding the latter's effort from the edge of the penalty area, while Tresor Kandol saw his header from a corner flash wide.
Jonathan Douglas let fly from 30 yards without troubling Cardiff goalkeeper Neil Alexander, but Leeds more than held their own in the open stages.
Goalscoring chances were few and far between and it was Leeds who began to dominate as the first half wore on.
Douglas's left-foot shot from 12 yards was blocked by Cardiff defender Joe Ledley as the Republic of Ireland international and his skipper Kevin Nicholls out-muscled Cardiff's Walton and another former Leeds player, Stephen McPhail, in central midfield.
Chopra and Walton were both booked for ill-timed tackles, while Leeds were dealt a double blow when centre-back Manuel Rui Marques was forced out of the action through injury and replaced by Hayden Foxe before Chopra gave the Welshman a lead they barely deserved.
Cardiff came out full of confidence for the second half and were denied a second goal by Ankergren, who first denied Steve Thompson and then Peter Whittingham.
The Dane held Thompson's header from Whittingham's free-kick before blocking Whittingham's close-range shot.
Leeds manager Dennis Wise sent on Richard Cresswell and fit-again David Healy for Blake and Westlake and then saw referee Mark Clattenburg turn away strong appeals for a penalty when Kandol went tumbling in the box under McNaughton's challenge.
Clattenburg then evened things up when showing goalscorer Chopra his second yellow card for a late challenge on Hayden Foxe, with Cardiff reduced to 10 men in the 66th minute.
In an action-packed second period the home side were awarded a penalty four minutes later when Kandol handled, but Thompson's firmly-struck spot-kick was brilliantly turned away by Ankergren.
Healy was off target with a 25-yard shot, but Leeds were given further hope with six minutes remaining when Cardiff were reduced to nine men.
Lifelong Leeds fan Walton was shown a second yellow card for dissent after Clattenburg waved away appeals for a free-kick and followed Chopra down the tunnel. Armando Sa shot wide, Eddie Lewis saw his effort blocked by Chris Gunter and Douglas' shot was well-saved by Alexander in the closing stages.
Leeds assistant boss Gus Poyet felt it was an opportunity to gain points that his side had failed to grasp.
He said: "We have missed a great chance of getting something from this game.
"But when you are down there at the bottom something always seems to happen.
"Crucially they scored when we were down to 10 men and after that we were always chasing the game.
"I think it was the best 30 minutes we have played away from home this season but we should have created more when they were down to nine men.
"It was a very strange game and the referee made some even stranger decisions.
"When you are down there no-one will help you but we must pick ourselves up for the next match."
Jones was full of praise for the way his side battled away, although was far from happy with the performance of referee Mark Clattenburg.
"As far as my players are concerned they were magnificent and although we have slipped out of the play-off positions despite winning I am not too worried," he said.
"If you are not good enough for the Premiership then you shouldn't referee in the Championship.
"The red and yellow cards handed out today were in the main for nothing challenges and at one stage I didn't know how many players I would end up with."