Barnsley conceded a late goal and had teenage defender Mason Holgate sent off in a derby defeat at Doncaster Rovers on Saturday.
The Reds were second best for the whole match as Donny missed a host of chances before substitute Harry Forrester eventually curled in a wonderful goal with five minutes left.
Holgate then lunged in on Richie Wellens in injury-time and was shown a straight red card. The result leaves the Reds 16th in League One, seven points off the play-offs and three above the relegation zone.
Barnsley boss Danny Wilson made four changes from the side that beat Yeovil Town 2-0 a week earlier. Peter Ramage could not recover from his thigh injury in time and was replaced at centre-back by Lewin Nyatanga who returned after illness. Ben Pearson was also out while Leroy Lita and Paul Digby dropped to the bench. In came Milan Lalkovic, Dale Jennings and Luke Berry.
In an attacking line-up, Conor Hourihane and Berry played in central midfield with Alex Kiwomya and Jennings on the wings and Lalkovic just behind striker George Waring.
Rovers totally dominated the first half and would have been three or four goals up if their strikers had taken their numerous chances. Nyatanga almost gifted Curtis Main a goal after seven minutes when he lost the ball in his own box but the Donny striker fired wide when clean through. Either side of that glaring miss, Main's striker partner Theo Robinson also had two chances from right wing crosses but put both of them wide.
Main then stabbed another glorious opportunity wide after meeting a fine Coppinger cross while Barnsley's only shot on goal of the match was an ambitious 35-yard attempt from Jennings out of the left wing after 40 minutes.
Donny were not as dominant after the break but continued to be the only side creating chances as Ross Turnbull denied a one-on-one for Coppinger and saved an Andy Butler header.
Forrester eventually broke the deadlock as he cut in the from left and curled a fantastic 20-yard shot into the top right corner.
