DERBY County's long unbeaten run against Leeds United was ended by a 2-0 defeat at Elland Road.
The Rams had not lost in 12 meetings against their Yorkshire rivals but two goals from Mirco Antenucci gave the hosts all three points from Saturday's Championship clash.
Despite the result, Derby remain top of the table, thanks to Millwall holding Bournemouth to a 2-2 draw.
Derby created arguably their best opportunity of the first half as early as the sixth minute.
Omar Mascarell's high ball over the top found Chris Martin onside in the box but his control took him away from goal and the chance was gone.
Clear-cut chances were few and far between as referee Mick Russell was kept busy, with a number of yellow cards handed out.
Antenucci fired over, off balance, after turning Richard Keogh in the 34th minute.
A minute later, Alex Mowatt shrugged off Mascarell and his well-struck 20-yarder was pushed away by the returning Lee Grant.
Soon after that, Antenucci blazed over from an angle following a Leeds corner.
Souleymane Doukara drove a low shot wide from outside the area - as the hosts increased the pressure.
And they got the breakthrough in the 42nd minute.
Mowatt got the better of Hughes in a battle for possession on the edge of the Derby area and the midfielder's low cross from the left was side-footed home by the unmarked Antenucci, eight yards out.
Leeds doubled their advantage five minutes into the second half.
Mowatt fed former England international Stephen Warnock on the overlap and his cross from the left found Antenucci, unmarked again.
This time, he had time to take a touch before placing a shot wide of Grant from 12 yards.
Grant had to be alert to stop Derby going further behind, keeping out a shot from full-back Sam Byram.
Just before the hour, Christie was tripped right on the edge of the box but a free kick, rather than a penalty was awarded.
Mascarell fired the free kick into the wall.
The visitors made a triple change, bringing on Craig Bryson, Simon Dawkins and debutant Kwame Thomas.
Leeds might have added to their lead, though, with Antenucci denied his hat-trick by a good save from Grant before the same player fired narrowly over.
Derby almost pulled a goal back nine minutes from time.
Bryson, whose low centre for Martin had been cut out, laid the ball back to Thomas, who blazed over from 10 yards.
LEEDS UNITED: Silvestri, Byram, Cooper, Bellusci, Warnock, Cook, Bianchi (Austin, 68), Mowatt, Adryan (Tonge, 90+5), Antenucci, Doukara. Other subs: Taylor (gk), Berardi, Pearce, Dawson, Sharp.
DERBY COUNTY: Grant, Christie, Keogh, Shotton, Forsyth, Mascarell (Bryson, 66), Hendrick, Hughes, Russell (Thomas, 66), Ibe (Dawkins, 66), Martin. Other subs: Roos (gk), Buxton, Eustace, Coutts.
REFEREE: M Russell (Hertfordshire).
ATTENDANCE: 26,028.
