Derby players went over to confront Ryan Yates after the midfielder made a rough challenge on Duane Holmes in the first half of the East Midlands derby.
As the ball was going out of play Yates dived into a dangerous sliding tackle on Holmes, trying to hook the ball from him to keep it in play.
The Derby player reacted angrily and pushed Yates as he was about to make his way up from the turf.
Both sets of players then ran across as tempers flared, with Yates running away from the melee as it unfolded.
Referee Robert Jones sprinted over to manage the scuffle, and all of those involved eventually calmed down.
Holmes was shown a yellow card for his aggressive reaction to the challenge, while Yates, who had fled scene, was called back by Jones and given the same caution.
Nottingham Forest fans were divided in their response to the decision to caution their midfielder, with one Twitter user posting: “Never a yellow for Yates.”
Another was more considered, writing: “Neutral fan here, Yates chopped him in half, 100% a yellow Holmes slightly lucky to stay on though.”
Derby fans were more angry at the referee’s decision to not send off Yates.
“Should’ve been red,” one simply wrote, while another joked: “At last a bit o spine.”
The incident came midway through a first half which was ignited within 73 seconds.
Yohan Benalouane prodded Forest ahead in the second minute to give Martin O’Neill’s side the advantage in the local derby.