This may have been Derby's first defeat of the campaign but the manner of it will have alarmed most at Pride Park on Tuesday night.
The Rams lacked quality all over the pitch when it mattered, failing to create enough chances and only a spirited final ten minutes or so threatening to save them after Jack Marriott pulled a fine goal out of nowhere to reduce what had been a 2-0 half-time deficit.
That had come despite the hosts arguably having the better openings in a first-half that ultimately saw them undone by two poor goals from a defensive point of view, City able to take those gifts and turn them into points-winning moments.
A change of formation at half-time was initially welcome but failed to spark enough of a change in fortune, too many players failing to perform and only Marriott looking like he'd have the ability to unlock the door.
The end result was frustration for the fans and question marks hovering over just how many options Phillip Cocu really has at his disposal when times get hard.
City looked the more threatening in the early stages and Andi Weimann saw a shot well blocked by Rams defender Matt Clarke seven minutes in when the ball broke to the former Ram in the penalty area.
And it was the visitors who would get the lead on 16 minutes. Derby failed to deal with an attack that ended with Kasey Palmer mis-hitting a shot into the ground, Benik Afobe flicking the ball on and it somehow landing at Weimann's feet and he was able to put Kelle Roos on the floor before sliding the ball home from six yards out.
At the other end, Derby responded with Mason Bennett breaking into the penalty area but seeing his shot deflected over the top, the corner being headed down by Richard Keogh but just out of the reach of Tom Huddlestone at the far post.
Then Kieran Dowell should have done better with a left-footed strike from ten yards after a good burst down the right from Max Lowe but his shot was blocked by a defender, before Tom Lawrence was denied by a fine block from City keeper Daniel Bentley after Bennett's cross had reached him at the back post six yards out.
But City would get a second largely against the run of play as Scott Malone gave the ball away at left-back and allowed Weimann to cross low to Josh Brownhill who swept the ball home from 12 yards out in first-half stoppage time.
Derby altered things at the break to go three at the back and introduce Florian Jozefzoon as right wing-back, allowing Lowe to return to his more familiar left side. Krystian Bielik dropped in between Keogh and Matt Clarke in central defence. Jozefzoon, however, would again fail to produce a successful cross throughout his time on the pitch.
Lawrence sent a dipping free-kick just too high early on as the Rams began well, but despite plenty of possession they again frustrated in the final third as they were often crowded out by a Robins side happy to play on the counter.
The Rams struggled throughout the half, devoid of creativity and quality all over the pitch and unable to create any clear cut chances.
Then, with five minutes to go, sub Marriott found some space 25 yards out to turn and fire a fine strike into the top corner and reduce the arrears, highlighting perhaps why he deserves a starting berth given his work-rate since appearing from the bench with 22 minutes left.
Lowe saw a shot deflected just wide as the game neared the end of five minutes of stoppage time, goalkeeper Roos not far away from getting his head on the corner having gone forward.
But there was neither enough time nor weaponry available for the Rams to force what would have been a fortunate draw, and instead a first defeat of the campaign was confirmed.
21 Kelle Roos
5 Krystian Bielik
6 Richard Keogh (c)
8 Kieran Dowell
9 Martyn Waghorn
10 Tom Lawrence
16 Matt Clarke (Jason Knight 80)
20 Mason Bennett (Jack Marriott 68)
25 Max Lowe
44 Tom Huddlestone
46 Scott Malone (Florian Jozefzoon 46)
Subs not used:
Ben Hamer, George Evans, Curtis Davies, Lee Buchanan
GOALS: Marriott 85
1 Daniel Bentley
2 Jack Hunt (Pedro Pereira 82)
6 Nathan Baker
8 Josh Brownhill (c)
14 Andi Weimann
22 Tomas Kalas
23 Taylor Moore
25 Tommy Rowe
40 Benik Afobe (Famara Diedhiou 70)
42 Han-Noah Massengo
45 Kasey Palmer (Callum O'Dowda 59)
Subs not used:
Rene Gilmartin, Sammie Szmodics, Antoine Semenyo, Niclas Eliasson
GOALS: Weimann 16, Brownhill 45+1
Ref: Stephen Martin