Huddersfield Town lost out to George Thorne's early second-half strike as well-drilled Derby County made it six wins in eight games.
Harry Bunn pegged back the visitors after they had had taken an early lead through Chris Martin as a disjointed first half finished level.
But there was to be no second equaliser and it was Derby who looked the likelier to score as the game wore on and Town slid to only their second defeat in seven.
Town were unchanged after Tuesday's 2-0 home win over MK Dons while Derby brought in Craig Forsyth for Stephen Warnock at left-back.
LOOK: Match Action from Huddersfield Town 1 Derby County 2 at the John Smith's Stadium
Midfielder Jacob Butterfield returned to the John Smith's Stadium to face his former club after his £5m move to the East Midlands on the last day of the transfer window.
Town forced a couple of early corners, but both were cleared, while Derby's Johnny Russell had a well-struck free-kick deflected off course.
The visitors went ahead in the 15th minute when Martin shot home after a scuffed effort by Russell fell into his path, with Town's claims of offside ignored.
Both sides made substitutions because players had taken knocks, with Mustapha Carayol replacing Sean Scannell for Town and Andreas Weimann coming on for Tom Ince.
The home leveller came in the 31st minute, with Bunn forcing the ball home after Ishmael Miller's shot bounced down off the underside of the bar
It took a fine save by Jed Steer to deny Derby a second when defender Jason Shackell met a Russell corner with a powerful header.
The on-loan Aston Villa stopper then saved a Bradley Johnson header and a Thorne shot to keep his side on level terms up to half-time.
Derby were back in front three minutes into the second half through Thorne, who drilled home a sweet shot after Joel Lynch headed clear a Butterfield cross.
Town found it hard to make much impact up front while Derby looked lively on the counter and tested Steer through Cyrus Christie.
The keeper then twice thwarted Martin, once from a header, then a shot as he cut in from the left after good work by Weimann.
Jamie Paterson replaced Town scorer Bunn and showed neat footwork before whistling a shot narrowly off target.
Flo Bojaj came on for Miller in the home team's final change, and while Town had a late flurry of pressure, Derby held firm.
