Paul Hart's Forest took three points and scored three goals in an action-packed 90 minutes, but this was at the expense of having David Johnson stretchered off after ten minutes.
Forest wasted some good chances early on, with both Mathieu Louis-Jean's and Johnson's shooting let them down.
Ten minutes into the match Johnson, battling for the ball, fell awkwardly and had to be taken to hospital for x-rays.
Hart then had to bring on newly-signed Gareth Taylor. With 30 minutes gone Forest finally got the goal they richly deserved, Marlon Harewood was awarded a penalty after he was brought down by Robert Page and it was Harewood who converted the penalty.
United offered no real form of attack and only managed one shot in the whole of the first half and this was in the 45th minute.
Minutes into the second half Paul Peschisolido missed a golden chance when he was left unmarked six yards out, but with only the keeper to beat the Canadian blasted wide.
Against the run of play Michael Dawson brought down Michael Tonge and for the second time of the game Mr Pike pointed to the penalty spot and Peter Ndlovu converted.
Minutes later and before the Sheffield players and fans alike had finished celebrating their equaliser, Harewood broke free of a disoriented defence and one on one with the keeper he neatly slotted home for the second of the afternoon and the fifth of this season.
On the hour mark Andy Reid and Chris Morgan clashed and the ref was called into action again, this time producing a red card for violent conduct after striking Reid.
With 20 minutes to go Forest got their third and best goal of the day an accurate through ball found Reid who struck the ball first time ten yards out leaving Paul Gerrard helpless to save.
Forest kept possession and blocked off the openings that the ten-man Blades were creating.