Results may matter little in pre-season but this one will have left Frank Lampard a little perplexed.
Derby, dominant in possession in the first-half and looking more than comfortable, were ultimately beaten by League Two Mansfield who rallied late on to score three in the last half-hour.
It will have been a sobering evening for Lampard that he'll have learned a lot from, although perhaps more in the negative sense than he'd have expected.
And whilst it's hard to judge too much from a game where the Rams used 21 players in total, there will have been an alarm bell or two ringing nonetheless.
The Rams were nearly ahead inside three minutes when Luke Thomas was found on the right hand side of the penalty area and his shot deflected off Krystian Pearce and came back off the crossbar.
Cameron Jerome then tried his luck from just outside the penalty area but his shot lacked power and rolled past Conrad Logan's left-hand post.
Tom Lawrence cut inside before firing high and wide as the Rams continued to have the lion's share of possession, Thomas doing similar from the other side and coming much closer as his effort just cleared angle of post and bar.
Mansfield's first effort of note came 23 minutes in when good pressure ended with Neal Bishop firing low at Scott Carson.
Andre Wisdom's fine through pass then found Thomas who this time saw his shot blocked by Logan, the young wide player enjoying plenty of the ball.
The Stags were reliant mainly on efforts from range, Otis Khan finding the hands of Carson on 36 minutes, the Rams on the other hand utilising a fair bit of width without really getting too much in the way of quality into Cameron Jerome up front.
Half-time arrived with the game scoreless.
Mansfield started the second-half well but it was the Rams who broke to nearly go in front on 55, Thomas and Lawrence combining to feed David Nugent who placed his shot against the outside of the far post and the ball went safe.
The Stags went in front on 65 thanks to a real mess at the back from the visitors, keeper Kelle Roos and defender Alex Pearce making a mess of clearing the ball and Jordan Graham nipping in to win the ball and chip Roos for the lead.
Derby were level within five minutes. Bradley Johnson's low shot from distance was parried by Bobby Olejnik but Nugent was able to retrieve the ball and square to Mason Bennett who had ghosted in unnoticed to fire low into the net from six yards out. Stags suffered from having defender Nathan Cameron off the pitch injured at the time.
But the hosts were soon to be back in front again as Lee Angol broke into the box only to be felled by a clumsy Jayden Bogle challenge, Angol dusting himself down to slot the penalty past Roos for 2-1.
Richard Keogh was then denied by Olejnik when a Derby corner wasn't dealt with, but the hosts would break away to score again two minutes later.
They got from back to front with relative ease and when Angol was found in the area he squared to CJ Hamilton who slid the ball into an empty net.
And that was that - the Rams unable to claw a way back and the Stags leaving their fans by far the happier with their team's evening's work.
Mansfield: Logan (Olejnik 46), White (Hamilton 59), Benning (Sterling-James 59), Preston (Graham 59), Pearce (Cameron 59, Blake 73), Bishop (Digby 59), MacDonald (Mellis 59), Davies (Butcher 59), Khan (Angol 59), Atkinson, Walker (Gibbons 59).
Derby: Carson (Roos 46), Hanson (Bogle 46), Lowe, Wisdom (Keogh 46), Davies (Pearce 46), Huddlestone (Johnson 46), Thomas (Bennett 63), Bryson (Butterfield 72), Jerome (Nugent 46), Ledley (Thorne 46), Lawrence (Blackman 72).
Sub not used: Mitchell
Ref: Ross Joyce
Att: 4.058 (1,394)