Nine-man Leeds are just one win away from ending their two-year exile from the Premiership after two goals in the space of four minutes from Rob Hulse and Frazer Richardson settled their play-off semi-final with Preston.
With the first leg ending in a 1-1 draw at Elland Road on Friday, North End enjoyed the better of the first half but Leeds' double strike just before the hour put them into the Championship play-off final against Watford or Crystal Palace a week on Sunday.
United, who had six other players cautioned, had defender Stephen Crainey and Richard Cresswell both sent off for two yellow cards.
But despite North End's Tyrone Mears having a goal chalked off, the hosts could not get back into the game.
It was a bitter contest which included a power failure at half-time, second-half crowd trouble and a number of melees involving the two sets of players.
But exactly five years since they reached a Champions League semi-final against Valencia, United took a major step back towards the top flight.
With the tie so finely poised after the first leg, Preston boss Billy Davies tried to grab the initiative with an offensive line-up that included four strikers, while Leeds initially looked content to contain.
North End started on the front foot, with midfielder Brian O'Neil drilling just wide with just over a minute gone.
However, Preston suffered a blow after nine minutes when bustling striker Brett Ormerod was stretchered off after lengthy treatment following a challenge from Jonathan Douglas, with reports later suggesting he had a suspected broken leg.
As Preston took time to adjust to their new shape following the introduction of substitute Simon Whaley the game grew scrappy and the two sides needed little encouragement for the niggles to start.
It took almost half of the first period for there to be a shot on target but North End goalkeeper Carlo Nash had to be at full-stretch to hold Richardson's powerful half-volley from just outside the area.
Almost immediately at the other end a Graham Alexander corner was headed back across goal by O'Neil but Danny Dichio failed to make sufficient contact with his own header to trouble Neil Sullivan.
Six minutes before the interval, Mears found space on the right flank and crossed for Dichio but the big striker was guilty of a bad miss as his header flew wide.
As the whistle for half-time went, the ground was plunged into semi-darkness due to a power failure in the area around Deepdale.
The floodlights eventually came back on and the second half kicked off 33 minutes later.
Leeds started the second period with more purpose and a Richardson cross sparked panic in the Preston box before the ball was hooked clear by Claude Davis.
Leeds were starting to push their hosts further and further back and they broke the deadlock 10 minutes after the break.
From Kelly's corner, Hulse's run was not tracked and he made no mistake to thump a header past Nash.
And Richardson looked to have put the tie beyond Preston's reach with a second goal four minutes later.
From a spell of pressure down Leeds' left, Liam Miller fed Hulse, who put the ball through a defender's legs and picked out Richardson at the far post for the midfielder to sneak the ball past Nash despite the goalkeeper getting hands to it.
Crainey had been booked just before the hour for kicking the ball away and he saw red in the 68th minute for tripping David Nugent as the striker headed towards the box.
Sullivan pushed Paul McKenna's resulting free-kick just wide but despite enjoying a numerical advantage, Preston were too frantic and the visitors were able to cope with what was thrown at them.
Sullivan tipped a Dichio header over and despite Mears heading the resulting set-piece past Sullivan, the referee ruled Alexander's corner had curled out of play.
Even though Cresswell was booked for a second time for kicking the ball away, the visitors held on for six minutes of added time to book their place in Cardiff.
Nine-man Leeds are just one win away from ending their two-year exile from the Premiership after two goals in the space of four minutes from Rob Hulse and Frazer Richardson settled their play-off semi-final with Preston.
With the first leg ending in a 1-1 draw at Elland Road on Friday, North End enjoyed the better of the first half but Leeds' double strike just before the hour put them into the Championship play-off final against Watford or Crystal Palace a week on Sunday.
United, who had six other players cautioned, had defender Stephen Crainey and Richard Cresswell both sent off for two yellow cards.
But despite North End's Tyrone Mears having a goal chalked off, the hosts could not get back into the game.
It was a bitter contest which included a power failure at half-time, second-half crowd trouble and a number of melees involving the two sets of players.
But exactly five years since they reached a Champions League semi-final against Valencia, United took a major step back towards the top flight.
With the tie so finely poised after the first leg, Preston boss Billy Davies tried to grab the initiative with an offensive line-up that included four strikers, while Leeds initially looked content to contain.
North End started on the front foot, with midfielder Brian O'Neil drilling just wide with just over a minute gone.
However, Preston suffered a blow after nine minutes when bustling striker Brett Ormerod was stretchered off after lengthy treatment following a challenge from Jonathan Douglas, with reports later suggesting he had a suspected broken leg.
As Preston took time to adjust to their new shape following the introduction of substitute Simon Whaley the game grew scrappy and the two sides needed little encouragement for the niggles to start.
It took almost half of the first period for there to be a shot on target but North End goalkeeper Carlo Nash had to be at full-stretch to hold Richardson's powerful half-volley from just outside the area.
Almost immediately at the other end a Graham Alexander corner was headed back across goal by O'Neil but Danny Dichio failed to make sufficient contact with his own header to trouble Neil Sullivan.
Six minutes before the interval, Mears found space on the right flank and crossed for Dichio but the big striker was guilty of a bad miss as his header flew wide.
As the whistle for half-time went, the ground was plunged into semi-darkness due to a power failure in the area around Deepdale.
The floodlights eventually came back on and the second half kicked off 33 minutes later.
Leeds started the second period with more purpose and a Richardson cross sparked panic in the Preston box before the ball was hooked clear by Claude Davis.
Leeds were starting to push their hosts further and further back and they broke the deadlock 10 minutes after the break.
From Kelly's corner, Hulse's run was not tracked and he made no mistake to thump a header past Nash.
And Richardson looked to have put the tie beyond Preston's reach with a second goal four minutes later.
From a spell of pressure down Leeds' left, Liam Miller fed Hulse, who put the ball through a defender's legs and picked out Richardson at the far post for the midfielder to sneak the ball past Nash despite the goalkeeper getting hands to it.
Crainey had been booked just before the hour for kicking the ball away and he saw red in the 68th minute for tripping David Nugent as the striker headed towards the box.
Sullivan pushed Paul McKenna's resulting free-kick just wide but despite enjoying a numerical advantage, Preston were too frantic and the visitors were able to cope with what was thrown at them.
Sullivan tipped a Dichio header over and despite Mears heading the resulting set-piece past Sullivan, the referee ruled Alexander's corner had curled out of play.
Even though Cresswell was booked for a second time for kicking the ball away, the visitors held on for six minutes of added time to book their place in Cardiff.