If there was one issue that this Pompey performance highlighted, it's the fact that should just one key player be missing from the side then the entire team will suffer.
David Nugent was missing due to a knee injury flaring up in training. That meant John Utaka had to be pushed up front, Liam Lawrence switched to left wing and Greg Halford played at right midfield with Joel Ward behind him at right back.
The result of those players being shuffled around was an unbalanced Portsmouth team being completely outplayed by a decent Derby side for the majority of the game.
Nigel Clough's men started brightly and would have taken the lead had Jamie Ashdown not pulled off one of the saves of the season by somehow getting his hand to Kris Commons' close range shot after Tomasz Cwyka cut the ball back to him.
Pompey responded with their only meaningful attempt of the first half as Dave Kitson forced a save from Frank Fielding with a long range effort, though the referee decided that Derby should have a goal kick.
Moments later the referee's assistant awarded the hosts a penalty after Aaron Mokoena clearly fouled Cwyka in the box. Given that the Pompey captain had already been booked, he may easily have been sent off for denying a clear goalscoring opportunity.
Robbie Savage stepped up and made no mistake from the spot to give his side a deserved lead.
Pompey continued to be disjointed in their play with nobody in a blue shirt performing well as Derby looked more likely to score as the first half ended.
The second half started well enough as Pompey improved their passing and created a couple of half-chances but it wasn't long before Derby doubled their lead after some poor defending allowed Paul Green to tap in a second goal after some link up movement with Cwyka.
Steve Cotterill changed things by replacing Joel Ward with Kanu, meaning Halford, Lawrence and Utaka could all move back to their proper positions.
The Nigerian should have pulled one back late on in the match after he managed to take the ball past the surrounding Derby defenders on the edge of the box, yet slashed the ball wide when it seemed easier to score.
Ashdown almost gifted Derby a third goal after his poor kick went straight to Commons who attempted to lob him, only for the Pompey 'keeper to just get his hand to the ball and prevent an embarassing goal.
Carl Dickinson was presented with the final chance of the game as Lawrence found him with a good cross-field pass but the left back fired wide from a difficult angle.
The referee blew for full-time and Pompey's unbeaten run was brought to an end. Simply put, we were beaten by the better team although some fans will point to Nugent's absense having a major effect on the balance of the team.
But there can be no complaints as a lethargic Pompey were second best for the majority of the match and I don't think Nugent would have made too much difference.
The people at the club say his injury isn't a serious one and I hope this is the case as we need to be at full strength for the visit of QPR on Tuesday.
In the meantime, Cotterill seriously needs to address our defensive problems because yet again, two silly mistakes have cost us and if we keep making these errors then any ambitions of promotion should be forgotten.
Pompey Player Ratings
Jamie Ashdown: 7 - World class save to deny Commons early on and redeemed himself by saving Commons' late lob.
Joel Ward: 5 - Not up to speed.
Ibrahima Sonko: 5 - Not as dominant in the air as he should have been.
Aaron Mokoena: 5 - Could easily have been sent off.
Carl Dickinson: 5 - Not very convincing.
Greg Halford: 5 - Cut a frustrated figure.
Michael Brown: 5 - Taken off late on as he may have been sent off.
Hayden Mullins: 5 - Not at his most effective.
Liam Lawrence: 5 - Couldn't influence the game from the left.
John Utaka: 5 - No service but wasteful when he had the ball.
Dave Kitson: 5 - Touch often let him down.
Richard Hughes (Brown 75): N/A - Brought on to prevent Brown being booked again.
Kanu (Ward 62): 5 - Missed a great chance.