Frank Lampard is heading back to Wembley after Derby pulled off a stunning comeback to break Leeds’ hearts.
Derby looked dead and buried when Stuart Dallas opened the scoring to put Leeds 2-0 up on aggregate.
But Lampard’s Rams showed the kind of determination he demonstrated as a player during his trophied career as they battled back to earn the perfect revenge for spygate.
Lampard’s substitution of Jack Marriott was pure genius and he scored with his first touch to level before half-time before netting the winner five minutes from time.
After making the play-offs on the last day, reaching Wembley is a tremendous achievement for Lampard in his first season as a coach.
The Lampards clearly like semi-finals at Elland Road and his dad, Frank Senior, did his famous dance round the corner flag here after scoring for West Ham to send them through to the 1980 FA Cup Final.
For Leeds there was only total despair and their 15-year exile from the Premier League goes on.
There will now be a question mark over Marcelo Bielsa and whether he will want to carry on for a second season in the Championship with his 64th birthday looming.
After a bright start by Derby, Leeds breached their defence for an eighth time this season on 24 minutes.
Patrick Bamford, back after his ban for playacting in place of the injured Kemar Roofe, won a free-kick on the left and when Kalvin Phillips swung the ball in, it came off the far post with Kelle Roos beaten and Dallas knocked it home.
Now Leeds were in full flight and Pablo Hernandez fed Klich, whose drive was deflected off Derby skipper Richard Keogh and against the underside of the bar.
Derby rallied after this lucky escape and Mason Bennett headed against the far post before Leeds threw them a lifeline just before half-time.
Marriott replaced Duane Holmes and seconds later with his first touch he scored into the empty net after Liam Cooper and Kiko Casilla made a mess of trying to clear Bennett’s header.
The tie then turned completely on its head when the Rams scored a second inside the first 40 seconds of the second half to level on aggregate.
Keogh found the exceptional Harry Wilson, who slipped in Mason Mount on the left and he cut inside Jamie Shackleton before dinking the ball over Casilla as he slipped.
Leeds looked stunned and from thinking about getting fitted for their play-off final suits, they were locked in a dogfight.
Derby were up for the scrap and now they were the ones pressing, harrying and forcing the errors from their opponents.
Their pressure brought a third goal on 57 minutes when Cooper pulled back Bennett in the box to concede a penalty and Wilson slotted home the spot-kick.
The action continued at a million miles per hour and Leeds levelled five minutes later when Northern Ireland international Dallas cut inside from the left and scored right-footed past Roos.
With so nine players on a caution, it was inevitable someone would be sent off in this highly-charged clash and sure enough, Gaetano Berardi was dismissed on 78 minutes for a late lunge at Bradley Johnson.
Derby made their man advantage count and after Wilson hit the post, Marriott scored the winner on 85 minutes.
Keogh won possession and played a one-two with Mount before releasing Marriott on the left, who finished expertly.
Even then the drama was not over and Scott Malone was sent off for a second bookable offence in stoppage time, but Derby held on a famous win.
