Marcelo Bielsa’s men went into the second leg a goal to the good thanks to Kemar Roofe’s strike at the iPro Stadium last Saturday.
And they looked to be on a smooth course to Wembley when Stuart Dallas put them 2-0 up on aggregate on Wednesday night.
Jack Marriott struck for Derby just before half-time, however, before Mason Mount levelled things up inside 60 seconds of the restart.
Leeds fans were soon sent further spiralling when Mason Bennett was brought down in the box by captain Liam Cooper.
On-loan Derby forward Harry Wilson slotted home the resulting penalty with ease to turn the tie completely on its head.
The drama did not stop there, though, with Dallas doubling up just after the hour mark to make the tie 3-3 on aggregate.
Dallas’ strike made it three goals in 17 minutes after half-time, sending fans into meltdown.
The game then got even more incredible as Gaetano Berardi and Scott Malone were sent off and Derby went 4-2 up on the night through Marriott.
“Heart beat monitor on the Apple Watch is quality. Went up to about 130. At a constant 90 now,” wrote one fan on Twitter.
“Can’t cope with this game, it’s killing me,” wrote another supporter.
A third carried on the theme: “Heart attack imminent.”
A Leeds fan tuning in at home said: “Shell shocked listening to this game.”
One Leeds supporter wrote: “I can’t take anymore of this. Suddenly wish I was one of those strange lads who picked whoever was top of the league table, regardless of where they are from.”
Referee Anthony Taylor bore the brunt of a fan’s criticism as they said: “Not saying this ref is card happy, but I’m pretty sure I just got booked for picking my nose.”
While Kiko Casilla was slammed too as one supporter wrote: “This Leeds keeper has taken a bung surely? I’ve never seen a man look so out of place on a football pitch.”
Another added: “Substitute the bloody keeper Leeds for goodness sakes.”
Derby will play Aston Villa in the Championship play-off final after beating Leeds 4-3 on aggregate and seeing Dean Smith’s side overcome West Brom in their semi-final tie.