Barclays Premier League
Gareth Davis reports from Pride Park Stadium
Robert Earnshaw came off the bench to net his first top-flight goal for the Rams but it won't be one to remember as Arsenal turned on the style to record a 6-2 success.
But, as with their defeat against Aston Villa, Derby had started the brighter of the two teams and could easily have been in front before Nicklas Bendtner opened the scoring.
Jay McEveley levelled matters but the visitors were back in front before half-time through Robin van Persie, then interval substitute Emmanuel Adebayor made it three shortly after the break.
Earnshaw's moment came with 14 minutes remaining, before Theo Walcott restored Arsenal's two-goal advantage.
Adebayor then ran in goals five and six for his second hat-trick against the Rams this season.
Dean Leacock and David Jones were ruled out through injury so in came Darren Moore and Jay McEveley in a move that saw Eddie Lewis return to the left of midfield.
There was also no place in the 16 for Kenny Miller, so Tito Villa led the line, while teenager Jason Beardsley was among the substitutes.
Arsenal, as expected, gave a Premier League debut to Polish goalkeeper Lukasz Fabianski and also included Alex Song, Denilson, Nicklas Bendtner and Theo Walcott from the start.
The visitors' early passing was slick, despite the greasy Pride Park surface, and they carved out the first opportunity five minutes in as patience down the left ultimately saw Bendtner cross to the far post where Emmanuel Eboue volleyed safely over.
Derby followed suit and after Villa dragged a Tyrone Mears cross wide, Mile Sterjovski saw his 20-yarder deflect off Song and dip just past the post with Fabianski well beaten.
Alan Stubbs was the next to threaten with a thunderous 30-yard free-kick that took a glance of the Arsenal wall and arrowed just off-target as the Rams continued their own bright start.
Mears, remaining on the right of midfield after starring there at West Ham, was once again involved with another fine cross that Villa rose to meet but he was also denied by an Arsenal deflection.
This was all inside the first 20 minutes, such was the visitors' failure to provide a serious attacking threat in the early stages.
But on 24 it was all-change as they took the lead with a goal that summed up Derby's problems.
Robbie Savage was caught in possession but the ball fell to Moore, whose pass was then charged down by Bendtner some 25 yards out.
Nicklas Bendtner opens the scoring for Arsenal. Picture by EMPICS Sport
The young Dane played a one-two with Robin van Persie and lined up a crisp finish beyond the advancing Roy Carroll from just inside the box.
It was decidedly against the run of play but a minute later the Gunners should have been two clear.
Walcott raced down the left and showed great composure to come inside on his right foot and ignore the obvious pass to Bendtner, instead picking out van Persie who had all the time in the world to pick his spot.
He did, but it was wastefully wide of Carroll's post - and how Derby made them pay before the half-hour mark.
Savage swung over a free-kick from the left and although McEveley didn't make a clean contact with his header, the ball dropped invitingly to be poked home from six yards.
The Rams' number four duly obliged for his second goal of the season following his Boxing Day finish against Liverpool.
At the other end Carroll produced a flying save to keep out a powerful effort from Cesc Fabregas, who had been quiet for the first 35 minutes.
And six minutes before half-time the visitors were back in front, this time via a goal crafted with more simple means.
Kolo Toure lifted a ball forward over the top of the Derby defence that found van Persie in behind, and this time the Dutchman made no mistake with a smart turn and finish from 15 yards.
There had been suspicions of offside but replays showed van Persie had timed his run to perfection.
And if going in at half-time a goal behind wasn't enough of a headache for the Rams, Arsenal chose the interval to replace van Persie with Emmanuel Adebayor, their leading scorer this season.
The second half's first opportunity was Arsenal's, a fizzing Toure effort that flashed just over the bar after Derby failed to clear their lines.
Toure was finding lots of ground down the right and arrowed in another shot eight minutes in that once again narrowly missed the angle of post and bar.
The shots rained in as Bedntner again tried his luck from distance and Derby had another escape on 57 as they were cut open by a quick break but Carroll's left foot came to the rescue as Adebayor closed in.
And the Gunners eventually made it three a couple of minutes before the hour-mark.
Walcott's pace took him away down the right and he pulled the ball back for Eboue, who somewhat stumbled into it but Adebayor was on hand to clean things up from a couple of yards out.
Emmanuel Adebayor leads the celebrations after making it 3-1. Picture by EMPICS Sport
Derby immediately withdrew Hossam Ghaly, who looked to have been struggling after an earlier fall, and replaced him with Benny Feilhaber - the American's first appearance since January 2.
Walcott really should have made it four after racing clear on to Bendtner's pass with Derby advanced in search of a goal back themselves.
But the visitors were really starting to strut their stuff and only last-ditch blocks by Andy Todd prevented Adebayor and then Walcott again from making it four.
Robert Earnshaw was thrown on in place of Sterjovski as Derby, still only the two goals behind, changed things around on 68 minutes.
Feilhaber was looking lively in the middle of the park and came as close as anyone to pulling a goal back 18 minutes from the end with a strong run and fine shot that Fabianski parried and grabbed at the second attempt.
And the Rams were back in it on 76.
Todd won the ball in midfield and slipped a fine pass through to Earnshaw, who seized upon the opportunity to finish well past Fabianski for his first Premier League goal in a Derby shirt.
However, no sooner had Derby pulled things back than their deficit was back to two again.
Walcott had been threatening to cut in from the left and find the far corner all evening and he finally delivered within two minutes of Earnshaw's strike to restore Arsenal's two-goal advantage.
Seconds later it was five as Clichy skipped away down the left and crossed low for Adebayor, who must have been close to running offside, to finish well past the exposed Carroll.
Earnshaw's sharp control and shot three minutes from the end forced Fabianski into another smart block but with time ticking down it would only have been another consolation strike.
Adebayor wrapped things up in stoppage-time as he raced on to a long ball and rounded Carroll before finishing well from a narrow angle.
DERBY: Carroll, McEveley, Stubbs, Villa, Lewis, Todd, Sterjovski (Earnshaw 68), Moore, Mears, Ghaly (Feilhaber 59), Savage (C).
SUBSTITUTES: Price (GK), Edworthy, Beardsley.
ARSENAL: Fabianski, Fabregas, Toure (Djourou 76), Gallas (C), van Persie (Adebayor HT), Denilson (Gilberto 63), Song, Clichy, Bendtner, Eboue, Walcott.
SUBSTITUTES: Almunia (GK), Senderos.
ATTENDANCE: 33,003 (3,063 visiting fans).