Derby have apologised to the family of the late Nottingham Forest owner Nigel Doughty over offensive chants from its supporters during the npower Championship clash at Pride Park on Tuesday night.
Jake Buxton's injury-time header gave Derby a dramatic 1-0 victory over their east midlands rivals.
But the post-match talk was dominated by shocking chants about Doughty, who was found dead at his home at the age of 54 last month.
A statement released by the Rams on Wednesday morning said: "Derby County Football Club wishes to formally apologise to the family of Nigel Doughty, Nottingham Forest Football Club and all supporters in attendance at Pride Park Stadium on Tuesday night for the behaviour of a small group of people at last night's game.
"Some of the chants directed to opposing supporters were wholly inappropriate and damage the excellent reputation of the club and its supporters at large.
"Chief executive Tom Glick has already apologised to club officials at Nottingham Forest, while manager Nigel Clough made his feelings clear in post-match interviews."
Glick added: "We are very disappointed that a brief moment of insensitive and distasteful chanting by a minority of supporters spoiled what was a great occasion at Pride Park Stadium last night and we do not condone the actions of those individuals in any way, shape or form.
"The vast majority of our supporters come to Pride Park to enjoy watching and cheering the Rams on to victory and generate a positive atmosphere inside the stadium.
"It is a shame for this majority that we today have to focus on a small group of people whose actions reflect badly on us all."
Derby have vowed to conduct a review of all aspects of last night's game, and the club have requested that supporters with any relevant information come forward and contact safety & operations manager Nigel Wood in total confidence on 0871 472 1884.