Leeds take a 1-0 lead into the second leg of the semi-final tie, after Kemar Roofe scored a second-half victor at Pride Park in the first leg.
Earlier in the season Leeds were fined £200,000 for breaching the EFL's code of conduct when they sent a member of staff to watch a Derby training session before a Sky Bet Championship match between the two clubs in January.
It is the first time in the history of the play-offs that a side has reached the Championship play-off final after losing the first leg at home.More news: Pilots confronted Boeing about 737 Max before second crash
The incident prompted the following chant from Leeds fans in Lampard's direction, to the tune of Oasis's Stop Crying Your Heart Out.
Leeds took the lead in the second leg, at Elland Road, but in a topsy turvy brilliantly dramatic game Derby came back to win 4-2 on the night and 4-3 on aggregate, to grab their place in the final against Aston Villa.More news: Campaigning in WB to end tomorrow after EC's unprecedented action
Derby County manager Frank Lampard celebrates following their triumph over Leeds. I'm not gonna lie.
If Leeds do not manage to surpass Derby on Wednesday night, serious question marks will be asked given the strength of the position they are now in. "I thought we were still in the game then but I'll admit that goal came at just the right moment".
The score remained level as the teams fought tooth and nail to regain the advantage, but it was Frank Lampard's team who eventually got the all important goal, as Marriott once again stepped up to dink a shot over Casilla after a marauding run from captain Richard Keogh in the 85th minute.More news: Bitcoin tops $8 000 as resurgence of cryptocurrencies goes on
The manager even laughingly pretended to wipe away tears as he sang the final line as Derby got the last laugh on Leeds, beating them for the first time in what was their final of four meetings this season.