Wanderers’ unbeaten League One run came to an end as Derby took the points to keep their own play-off push in top gear.
With both sides defending healthy undefeated records and locked together in the top six it looked like something had to give.
And unfortunately for the Whites it was Derby who kept their bandwagon rolling as a goal in each half was enough to give the Rams a fifth win in six league games.
With Wanderers not matching their recent heights and unable to hit back until substitute Kieran Sadlier’s injury-time strike, Ian Evatt’s men suffered a first defeat in nine games.
Dan Nlundulu, on his first start, and the introduction of teenager Shola Shoretire provided bright spots but the Whites will be now looking for a positive response when they face Forest Green Rovers on Tuesday night with the chance to stay in the thick of the play-off race.
These two sides couldn’t be separated in a goalless draw at the University of Bolton Stadium at Christmas but it took just 16 minutes for the deadlock to be broken in the return as Derby went ahead.
Wanderers looked as though they had come through an early examination but conceded just a second goal in seven league games when Nathaniel Mendez-Laing met Tom Barkhuizen’s cross from the right on the stretch to steer the ball past James Trafford – possibly with the aid of a touch off defender Will Aimson.
Nlundulu – making a full debut in place of the injured Jon Dadi Bodvarsson – looked to lead the Wanderers’ response with some searching questions of a Rams’ defence not breached at home since October as they protected an 17-match unbeaten run.
Nlundulu was a willing target and excellent outlet for the Whites as others looked to play off him with Conor Bradley only inches away from meeting a pass for a clear run at goal following another burst forward from the on-loan Southampton striker.
The Whites looked a threat around the County penalty area but Derby continued to pose a danger on the break as they never allowed any of Evatt’s men to settle on the ball.
And when Mendez-Laing returned the favour for Barkhuizen, the winger had a heading chance which was comfortably dealt with by Trafford with half an hour gone.
Barkhuizen then saw a shot blocked but Wanderers were still very much in hunt as Eoin Toal got forward to deliver a dangerous cross which Kieran Lee could only poke goalwards as he and Nlundulu closed in.
With over 30,000 inside Pride Park – including a superb vocal following of more than 3,000 from Wanderers – the tempo was never allowed to drop as the Whites went in search of a second-half equaliser.
They made a decent start with Kyle Dempsey dipping a shot over the bar before Evatt made his first change with just over an hour gone as new loan signing Shola Shoretire was sent on to try and provide an added spark.
Wanderers kept probing but the crucial next goal needed to come their way and when Derby doubled their advantage with just under 20 minutes to go it was suddenly a long way back.
Derby hadn’t looked as potent since the break but they were ruthless in closing in on maximum points when Max Bird picked out Barkhuizen to head into the path of Conor Hourihane to stride into the box and drive home his third goal in as many league games.
With Nlundulu tiring Evatt sent on more fresh legs to try and mount a late fightback.
One of those substitutes made his mark as Sadlier drove in a smart finish from Dion Charles to claim a first league goal of the season - and fifth in total - in stoppage time to spoil Derby’s clean sheet record.
But there was not enough left the clock to worry the Rams further as Wanderers lost for just the second time in League One since the end of October on afternoon when they were ultimately second best.
Wanderers: Trafford; Toal, Aimson, Johnston; Bradley, Morley, Dempsey, R Williams (Sadlier 87); Lee (Shoretire, 63); Charles, Nlundulu (Kachunga 73). Substitutes: Jones, MJ Williams, Almeida Santos, Sheehan.
Derby: Wildsmith; Smith, Davies, Forsyth, Roberts; Bird, Hourihane; Mendez-Laing (Dobbin 83), Knight (Thompson 88), Barkhuizen (Springett 75); McGoldrick (Collins 75). Substitutes: Loach, Stearman, Rooney.
Referee: Jeremy Simpson
Attendance: 30,004 (Wanderers 3,139)