Derby progressed to the Championship play-off final after a sensational game involving six goals, nine yellow cards and two red cards at Elland Road.
After losing the first-leg 1-0 and then going behind early in the second-leg to Stuart Dallas’ goal, it looked a long way back for Frank Lampard’s side.
But a goal just before and after half-time courtesy of substitute Jack Marriott and Mason Mount levelled things up, before a Harry Wilson penalty put the visitors 3-2 ahead on aggregate.
Dallas’ brace pulled Leeds level again but, with just five minutes remaining, Marriott’s second of the game was enough to send the Rams to Wembley on May 27th.
Derby manager Frank Lampard said: “The personal feeling is up there with anything I have done.
“Of course, winning things at Chelsea, I was fortunate to do that, and they have to stand out because you want to win things.
“To get into the play-offs after such a great run and to go 1-0 down and do something that no team has ever done in the play-offs after losing the first leg at home, is great.
“I think it would be naive to say I absolutely believed it because this (Elland Road) is a hard place to come, we knew that from coming here in January but I had belief in the players and that grew over the last 24 to 48 hours because I saw a real desire in them.”
Leeds United Head Coach Marcelo Bielsa said: “As it’s a painful situation, we are very disappointed.
“I have to say that we had the conditions to finish first or second [in the table] and all the conditions to be the best team in the play-offs.
“When you can’t reach something that was reachable, it always puts doubt on the head coach.”
“It’s meaningless explaining that we had a many chances as the opponent in the second half and in the first we had more chances and should have made a difference.”