Match ends, Burnley 4, Derby County 1.
Burnley scored three times in 12 second-half minutes to go third in the Championship and extend Derby's winless period to five league games.
Derby's Richard Keogh headed Matt Lowton's cross into his own net on 29 minutes but Jacob Butterfield replied with a 20-yard volley within a minute.
Andre Gray and Sam Vokes both scored penalties before Scott Arfield's shot deflected in off Jason Shackell.
Burnley trail Middlesbrough in second by four points, with Derby fifth.
The Rams have taken only two points from their last five league games, although they perhaps did not deserve to lose by such a hefty margin to one of their main rivals for automatic promotion.
Chris Martin and Tom Ince forced saves from Burnley goalkeeper Tom Heaton before Keogh's own goal, and they had another good period of pressure after Butterfield's well-taken equaliser.
However, they were undone by a period of poor defending which saw them concede two penalties in four minutes after half-time.
Keogh tripped Gray who was jinking inside the six-yard box, allowing the Championship's leading scorer to net his 17th goal of the season, before ex-Burnley captain Shackell handled a right-wing cross and Vokes duly converted the resulting spot-kick.
On his return to Turf Moor, Shackell's evening was made worse when Arfield's low effort looped off his foot and over Scott Carson into the net.
While Derby are faltering, the Clarets are growing into genuine top-two contenders. Their manager Sean Dyche was able to select an unchanged starting line-up for the fifth game in a row, while they have scored 12 goals and let in just two during a three-game winning sequence in the Championship.
Burnley manager Sean Dyche: "We have to stay strong now. Some of our football was excellent in the second half, there was some real quality out there.
"Don't forget Derby are a very good side, but I'm delighted because now we've started scoring from all over the pitch and that does make a difference.
"Margins are tight at the top of the division, but we just have to keep working hard and keep scoring like that."
Derby head coach Paul Clement: "Things were looking positive at half-time, but that four or five-minute period in the second half proved costly for us.
"I'm not an idiot, though. We've lost 4-1 and we have to do better.
"That's been the difference - what happened in the two penalty areas. They defended theirs well and we didn't. I've no complaints about the penalty decisions.
"It's just been a night to forget."
- 9VokesSubstituted forMarneyat 89'minutes
- 7GraySubstituted forHenningsat 79'minutes
- 14ShackellBooked at 57mins
- 15JohnsonBooked at 68minsSubstituted forCamaraat 69'minutes
- 23InceSubstituted forRussellat 79'minutes
- 22BlackmanSubstituted forBrysonat 86'minutes
- Michael Oliver
- Shots on Target
Second Half ends, Burnley 4, Derby County 1.
Stephen Warnock (Derby County) wins a free kick in the attacking half.
Foul by Joey Barton (Burnley).
Attempt blocked. Chris Martin (Derby County) left footed shot from the centre of the box is blocked. Assisted by Cyrus Christie.
Corner, Derby County. Conceded by Michael Keane.
Corner, Derby County. Conceded by Ben Mee.
Foul by George Thorne (Derby County).
Joey Barton (Burnley) wins a free kick in the defensive half.
Substitution, Burnley. Dean Marney replaces Sam Vokes.
Substitution, Derby County. Craig Bryson replaces Nick Blackman.
Foul by George Thorne (Derby County).
Rouwen Hennings (Burnley) wins a free kick on the left wing.
Delay over. They are ready to continue.
Substitution, Burnley. Rouwen Hennings replaces Andre Gray because of an injury.
Substitution, Derby County. Johnny Russell replaces Tom Ince.
Delay in match Andre Gray (Burnley) because of an injury.
Attempt missed. Andre Gray (Burnley) right footed shot from more than 35 yards misses to the right.
Attempt saved. David Jones (Burnley) left footed shot from outside the box is saved in the centre of the goal. Assisted by Sam Vokes.
Corner, Burnley. Conceded by Scott Carson.