Anton Forrester and Josh King both got on the scoresheet on their return to action for the Under-21s on Monday night.
King's opener was followed by a brace from strike partner Forrester, but it was the Rams who clinched all three points with a second half comeback to edge a seven-goal thriller.
Rovers took the lead after just nine minutes at a sodden Ewood Park, King slipping the ball home from Jack Doyle's pass.
But the visitors levelled almost immediately, Alban Bunjaku turning well in the Rovers box to score.
Forrester soon restored Rovers' lead with a wonderful diving header from Connor Mahoney's cross, and ensured the blue and whites would lead at the break with a close-range strike just before half time.
The duo were replaced at the break and the Rams took full advantage, reducing arrears on 53 minutes when Tom Koblenz' long range effort was deflected home.
With their tails up the visitors sensed they could get more with Shaquille McDonald doing the damage. The winger levelled the scores on 69 minutes after converting Alfie Santos's cutback, before emphatically firing the Rams in front five minutes later after poor defensive play from Rovers.
Any chance of a comeback from the home side ended with ten minutes remaining when Hyuga Tanner was shown a straight red card to cap a disappointing evening at Ewood for Rovers.
It was a lively start at a rain-soaked Ewood Park as Rovers took the lead from their first attack of the match after just nine minutes.
There appeared to be little on as Jack Doyle sent a ball forward down the left but King turned his marker well to advance before firing low past Derby goalkeeper Jonathan Mitchell.
The Rams stopper will admit he should have done better, but it was the blue and whites who celebrated.
However the lead would last barely three minutes as Derby hit back almost immediately.
A superb turn in the box from striker Alban Bunjaku caught the Rovers defence out and he slipped the ball home past an unsighted Jake Kean.
Despite the terrible conditions it was an entertaining, competitive match, and just past the half hour it was Rovers who regained the lead.
It was a goal of high quality as a ball up to Anton Forrester was well shielded as the striker spread the play wide to Connor Mahoney. The winger took on his man before delivering a peach of a cross that Forrester converted with a fine diving header.
It was a great way for the forward to mark his return to action having been out of action for more than nine months with a serious knee injury.
The visitors responded well and were a whisker away from levelling a second time, Kwame Thomas just wide with a back post header from a corner.
Instead it was Rovers who stretched their advantage with a third goal before the break.
A ball into the box broke to Devarn Green and he found Forrester and although the striker's effort lacked purchase it deflected off a County boot to roll into the back of the net.
Jake Kean then ensured Rovers would lead 3-1 going into half-time with an outstanding save.
An excellent through ball from Rhys Sharpe saw Callum Guy in on goal, but the Rovers stopper made himself big enough to divert the effort around the post.
Neither King nor Forrester reappeared after the break, the strike duo impressing on their return following injury as Hyuga Tanner and Dean Rittenberg replaced them, but it was the Rams who were quickly out of the blocks to make it 3-2 on 53 minutes.
A short corner from the right was played to midfielder Tom Koblenz and his low shot through a crowded area deflected off a Rovers defender and trickled into the corner of the net.
Boosted by that goal the Rams went looking for an equaliser and it duly arrived on 69 minutes.
The visitors had already threatened in and around the box but those warnings weren't heeded as Alfie Santos got around the back of the Rovers defence to square for fellow wide-man Shaquille McDonald to blast home.
It would soon get worse for Rovers as sloppy defending saw them concede a fourth goal just five minutes later.
As three Rovers players went for the same ball towards the edge of the area, it was quickly shifted to McDonald, and he notched his second of the evening with an emphatic top corner finish.
To compound a poor second half showing, Rovers were reduced to ten men with just under ten minutes remaining.
A reckless over the ball challenge from Hyuga Tanner on Tom Koblenz resulted in the Rovers midfielder being shown a straight red card.
Despite Eric Kinder urging his side forward, without the twin threat of King and Forrester Rovers offered very little in the second half as an attacking force, and that enabled County to see out the closing stages to claim all three points.
ROVERS: Kean, Daly, Doyle, Bauress (c) (sub Preston 90+1 mins), Jones, Songo'o, Mahoney, Carson, King (sub Rittenberg 46 mins), Forrester (sub Tanner 46 mins), Green.
Subs not used: Crump, Lavelle.
Goals: King 9 mins, Forrester 31, 44 mins.
DERBY: Mitchell, Hendrie, Sharpe, Koblenz, Rawson, Hanson, Santos (sub Vernam 90+2 mins), Guy (sub Adams 83 mins), Thomas, Bunjaku, McDonald (sub Zanzala 89 mins).
Subs not used: Dryden, Behrens.
Goals: Bunjaku 12 mins, Koblenz 53 mins, McDonald 69, 74 mins.
Booked: Hanson, Hendrie.