Gregory left Pride Park under a cloud in 2003 and the away section at Loftus Road gave him a piece of their mind throughout.
He had made an unbeaten start to his Rangers tenure, but just as in a 3-3 draw against Norwich at the weekend, his side got off to a slow start and were behind after four minutes.
A long punt down field by goalkeeper Lee Grant was won by big Steve Howard up front. Morten Bisgaard was on hand to curl the knock down beyond Paul Jones.
But although Dexter Blackstock had the chance to make an instant response with a point-blank header from a Lee Cook cross, he failed to beat Grant.
Again just as on Saturday, it was left to on-loan midfielder Jimmy Smith to put his side back on level terms.
The Chelsea youngster admitted to being delighted with a goal on his home debut against Norwich, but this one on seven minutes was even sweeter.
As the Derby defence failed to clear a bouncing ball, Smith took the initiative by ramming home a volley from the edge of the box.
The goal threw the game wide open and the match itself continued to mirror the weekend's encounter at Loftus Road.
On that occasion, Paul Jones was forced to pull off a fantastic point-blank save from Norwich's Robert Earnshaw early in the first half. He did likewise from Arturo Lupoli after 18 minutes here.
Two minutes later, the 39-year-old pulled off an equally spectacular save from a rasping Seth Johnson free-kick destined for the top corner.
Although the home side had most of the ball, they could not turn their superior possession into goals and they paid the price on 33 minutes.
Derby left-back Mo Camara was able to advance down the left and put a cross in and, although Paul Jones once again did well to stop Lupoli's deflected shot, Howard was on hand to tap home.
Paul Jones' great saves continued into the second half as he denied Howard on 68 minutes.
But he could do nothing about a Jon Stead shot which hit the post and a Howard header which hit the bar just after.
The home side were falling to pieces and Adam Bolder will be kicking himself after failing to convert a Stead cross when unmarked three yards out on 71 minutes.
Rangers' best effort of the second half came from Marc Bircham six minutes from time, but his long-range shot was palmed away by Grant, while Blackstock and Martin Rowlands both missed great chances in the final moments.