Darius Henderson scored twice as Sheffield United fought off a second-half comeback from Derby to extend their unbeaten run to six Championship games.
With a resolution in the Carlos Tevez saga apparently close - United are reportedly near to agreeing a compensation payout with West Ham - the Blades consolidated their fourth-placed position in their bid to return to the top-flight with a hard-fought win at Bramall Lane.
The industrious David Cotterill laid on goals for Kyle Naughton and Henderson in the first half, but the visitors responded in a frantic second period.
Rob Hulse netted against his former club seven minutes after the interval before Henderson restored the two-goal lead.
But Derby cut the deficit again when on-loan Aston Villa midfielder Barry Bannan, on as a half-time substitute, lashed in on his debut after 69 minutes.
County, however, could not find a leveller and Craig Beattie struck a fourth for United in stoppage time as Nigel Clough suffered a third loss in 11 league games since he emulated his father Brian by taking the Rams reins on January 8.
United went in front after seven minutes when Cotterill exploited Paul Connolly's error on a foray forward with a mazy run down the left channel.
The Blades midfielder played a cross ball for right-winger Naughton, who had time and space to pick his spot with a curling left-foot effort from the edge of the area for his first league goal of the season.
United added a second after 21 minutes, with Cotterill again the provider.
He raced down the left to the byline and delivered a pinpoint cross for Henderson who headed between Stephen Bywater's legs for his first goal in seven games.
Derby's defence was less than convincing but United could not add to their tally before the interval with Henderson and Jamie Ward both flagged offside and Cotterill off target with a free-kick.
Hulse flicked a Robbie Savage free-kick straight at Paddy Kenny in first-half stoppage time before smashing in Derby's opener seven minutes into the second period.
Gary Teale caused havoc down the United right and his tame shot hit Matthew Kilgallon on the line.
Hulse was first to react, smashing into the roof of the net from six yards for his sixth goal in nine games.
The striker blasted off target before the Blades exposed Derby's defensive frailties once again.
Cotterill found Stephen Quinn down the left and he crossed for Henderson, who, with his back to goal, muscled his way round Martin Albrechtsen and tucked the ball into the bottom corner.
Derby immediately responded, Steve Davies beating Leigh Bromby on the left of the area and crossing for the diminutive Bannan - yet to train with County after signing on Friday - to power a left-foot shot in from eight yards.
Halford rampaged down the right and shot wide across goal after coming on and Hulse headed Barazite's cross at Kenny at the other end.
Davies headed wide late on and Hulse hit over in stoppage time before substitute Beattie, on loan from West Brom, tucked in his first Blades goal with the last kick of the game.
Teams:
Sheff Utd Kenny, Bromby (Halford 72), Morgan, Kilgallon, Naysmith, Cotterill (Beattie 83), Naughton, O'Toole, Stephen Quinn, Ward (Howard 90), Henderson.
Subs Not Used: Lupoli, Bennett.
Booked: O'Toole.
Goals: Naughton 7, Henderson 21, 62, Beattie 90.
Derby Bywater, Albrechtsen, Todd, Nyatanga, Connolly, Teale, Eustace (Bannan 46), Savage, Barazite (Villa 78), Davies, Hulse.
Subs Not Used: Kazmierczak, Price, Sterjovski.
Booked: Eustace, Todd, Hulse.
Goals: Hulse 52, Bannan 69.
Att: 27,565
Ref: Iain Williamson (Berkshire).