Derby County fell to a 1-0 defeat at Northampton Town in Sky Bet League One on Saturday afternoon.
A first half goal from Sam Hoskins was enough to hand the home side all three points and ensure the Rams tasted defeat for the first time in five games, ending their four-game winning run.
Chances were few and far between for both teams in a cagey opening 20 minutes at Sixfields Stadium. Midfielder Liam Thompson had the first of the day when he connected with a pull-back from Nathaniel Mendez-Laing but a Northampton defender was back to make a vital block.
A great chance fell the way of the Rams just moments later. A deep cross from Kane Wilson was met by Louie Sibley who knocked the ball back across goal for Martyn Waghorn, who fired over from close range.
The home side took the lead with their first effort of the afternoon. Louis Appere got down the left and crossed deep for Hoskins, who volleyed first time beyond Joe Wildsmith with an excellent side footed effort.
Paul Warne's side were agonisingly close to equalising immediately when Ebou Adams was the first to connect with a corner but he saw his goalbound effort blocked on the line and cleared.
Minutes later Adams went close again but this time he really should have scored. Wilson's pinpoint cross from the right found Adams unmarked six yards out, but the on-loan Cardiff City midfielder headed down into the ground and over the bar.
The Rams continued to press after the break in a bid to find an equaliser and nearly found one through Mendez-Laing. Wilson crossed low for the winger who slid in low but was denied at point-blank range by goalkeeper Louie Moulden.
The Cobblers were inches away from a second goal on the hour mark through Manny Monthe. Mitch Pinnock laid the ball out wide for Monthe who let fly from 25-yards but he saw his effort rattle the post before drifting out to safety.
Waghorn saw his effort hooked off the line by some last-gasp defending as the game became far more stretched as it entered the final 20 minutes.
Pinnock was close to killing the game in the dying minutes when he looked to fire beyond Wildsmith but he was denied by a brilliant block from defender Curtis Nelson.
Ten additional minutes were signalled giving the Rams a huge boost in their bid to find an equaliser.
Derby weren't able to create any real clear-cut chances in the final stages but there was drama when centre-back Sonny Bradley saw a straight red card branded his way after an off the ball altercation.
The Rams remain second in league table, four points clear of Bolton Wanderers in third, though they have now played one game more than the Trotters.
Northampton Town: Moulden (GK), McGowan (C) (62' Hondermarck), Sowerby, Sherring, Hoskins (90' Bowie), Fox (90' McWilliams, Appere (90' Simpson), Pinnock, Monthe, Leonard, Moore (90' Koiki).
Substitutes not used: Dadge (GK), Gape.
Derby County: Wildsmith (GK), Wilson, Hourihane (C), Bradley, Cashin, Waghorn (68' Washington), Mendez-Laing (68' Ward), Thompson (63' Blackett-Taylor), Sibley (63' Elder), Adams (63' Smith), Nelson.
Substitutes not used: Loach (GK), Radcliffe.
The Rams are back in action at Pride Park on Good Friday when Blackpool are the visitors in Sky Bet League One (3pm kick-off).
