No other team has defeated United more times than Derby since 2010, getting the better of their opponents 10 times.
When Tom Lawrence's free-kick was badly misjudged by 21-year-old goalkeeper Bailey Peacock-Farrell the Rams were swiftly level, but Ezgjan Alioski's ideal left-wing cross was headed in by Kemar Roofe to restore the Leeds lead.
And instead it was Derby who were able to level matters in the 12th minute after Liam Cooper fouled Lawrence on the edge of the box.
Leeds manager Marcelo Bielsa, speaking though an interpreter, said: "It was more clear during the second half but in the first half we suffered some actions that could have allowed our rivals to score goals".
After a busy deadline day, Lampard has four new Derby signings available with striker Martyn Waghorn looking to make his debut following his move from Ipswich Town.
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The quality of Leeds movement forward caused Derby problems from the start and it was no surprise when Mateusz Klich fired a low shot past Scott Carson in the fifth minute.
Dishing out a 4-1 win tonight, Leeds were relentless.
But there was nothing that Carson could do about a superb second goal for Roofe on the hour mark as the striker produced a sensational touch to turn Fikayo Tomori to work space for a deadly finish that was smashed into the net. Pablo Hernandez, Samu Saiz and Ezgjan Alioski support Kemar Roofe.
Leeds, after two incredible wins under Bielsa, are now favourites to win the league themselves.
It was Lawrence's late header last weekend that completed the comeback for Derby County against Reading and on Saturday, he showed that he's not too shabby with the ball at his feet either. Subs not used: Roos, Forsyth, Pearce, Marriott.