United again suffered post international break blues and in the process surrendered top spot in the Sky Bet Championship.
Chris Basham netted and the Blades were impressive in parts but goals from Craig Bryson and Jack Marriott gave Derby victory.
For the fifth consecutive game, boss Wilder named an unchanged starting XI, there was one change on the bench where Cranie was included for the first time.
The Blades suffered the worst possible start. No United player had touched the ball in the first 20 seconds when Derby opened the scoring. Wilson delivered from the left, Marriott laid off and BRYSON crashed the ball into the bottom corner of Henderson's net.
Recovering from the shock, United began to apply pressure and force the home side back. Crosses came in from both sides and Fleck had a shock blocked by Keogh, whilst Tomori cleared at the expense of a corner as Basham looked to poke home Freeman's cross.
Stevens produced a great interception to prevent Wilson's pass finding an unmarked Marriott after Basham was robbed, but the Blades were clearly the best side in the first half.
A patient build-up saw Stevens given space on the left but his shot was comfortably gathered by goalkeeper Carson, although the Blades were level before the break. Fleck glided through the home defence, beating four white shirts in the process before squaring for BASHAM to slot home.
Before the break, there was a chance for Derby to regain the lead but an unmarked Waghorn headed wide at the back post. In added time there was an opportunity at both ends in a matter of seconds, Henderson saved from Marriott and following a break, Duffy curled wide.
The start to the second half was even but the better of the chances came from the home side. Henderson pushed a shot from Lawrence over the crossbar, Waghorn curled over after cutting in from the right and Lawrence then fired wide.
Coutts and Clarke were introduced but the chances continued for the home side. Marriott turned Bryson's cross wide and an important touch from Stevens prevented the speedy Jozefzoon getting clear.
Derby did, however, regain the lead on 77 minutes. MARRIOTT got ahead of the defence to side-foot past Henderson from Forsyth's cross. A minute later Marriott went close to another but Egan deflected the striker's shot wide.
Washington replaced Basham in an attack-minded move but two opportunities inside a minute was all the Blades could muster late on. Carson dropped a Norwood corner but Mount cleared O'Connell's header off the line and then the goalkeeper atoned for his error by pushing away McGoldrick's shot.
The closing minutes, plus four added, saw Derby restrict the Blades and Carson's goal was not threatened before the final whistle.
Derby: Carson, Forsyth, Bryson (Lawrence 36), Tomori, Keogh, Wilson, Mount, Waghorn (Jozefzoon 71), Marriott (Davies 86), Bogle, Huddlestone.
Unused: Johnson, Roos, Nugent, Malone.
Blades: Henderson, Stevens, Fleck, O'Connell, Basham (Washington 80), Sharp (Clarke 65), Egan, Norwood, McGoldrick, Freeman, Duffy (Coutts 65).
Unused: Stearman, Johnson, Moore, Cranie.