The odds seemed against the Rams as they were a goal down from the first leg at Pride Park and no team had ever previously reached the second-tier final after losing the first leg at home.
Indeed, Leeds took the lead at Elland Road on Wednesday night and made it 2-0 on aggregate when Stuart Dallas tapped in after Liam Cooper's header had hit the post.
However, Jack Marriott drew Derby level with his first touch before half-time after a mix-up at the back between Cooper and Leeds goalkeeper Kiko Casilla.
Premier League loanees Mason Mount and Harry Wilson netted after the break to turn the tie around for Frank Lampard's side only for Dallas to drift in and fire Leeds back level on aggregate.
Leeds defender Gaetano Berardi was then sent off for a challenge on Bradley Johnson and in the end Marriott edged Derby back in front with a composed finish to claim a 4-3 aggregate win.
Morris, who had a short stint at Leeds in 2003-04, posted several tweets of his own as well as replying to a Rio Ferdinand message - the ex-defender also an Elland Road old-boy - and one from Derby's official account:
How bout them Rams??— Jody Morris (@morriskid) 15 May 2019
Wallop— Jody Morris (@morriskid) 15 May 2019
Here is how some Derby fans reacted to Morris's tweets:
Thank you so much, so proud of you all ❤️— lisa howard (@broad8133) 15 May 2019
You and your mate going out, can i come— David Correia Martins (@DCMartins81) 15 May 2019
Simply awesome.... Whatever happens from here on in, you and Frank will be Rams legends forever!!! COYR. Wembley here we come....— Carl A Hadfield (@carlhadfield) 15 May 2019
For the love of God don't you and Frank ever leave.— Matt T (@Tweddds) 15 May 2019
Thank you Jody. unbelievable..so happy for you all..COYR.— julie osbiston (@julesossie) 15 May 2019
All our are with you Jody and ur mate that u come through the next 24 hours unscathed— Alan Leah (@alan_leah) 15 May 2019
Derby will face Aston Villa in the Championship playoff final at Wembley Stadium on Monday 27 May.
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