Marlon King broke the deadlock against his former employers midway through an enthralling first half, although City's cheers were soon silenced as Forest turned things around within the space of 10 minutes.
Lewis McGugan, with his 11th of the season, levelled with a fortunate long-range shot which deceived Keiren Westwood.
Robert Earnshaw then converted amid a static Sky Blues defence who had momentarily stopped having seen Guy Moussi pull up with a strained hamstring before managing to whip in a cross.
The nature of the result only served to highlight the contrast in fortunes between the two sides who have somewhat traded fortunes over the second third of the season.
Forest, with just one defeat in their last 13, are now up to fourth in the table while Coventry have slumped from fifth to 15th on the back of a nine-match winless streak.
The Sky Blues suffered a big blow in the pre-match warm-up with the loss of returning midfielder Sammy Clingan, who was part of two changes from Saturday's 3-2 defeat to Birmingham.
And it will have left manager Aidy Boothroyd rueing the deadline-day loss of teenage prodigy Conor Thomas to Liverpool.
Forest also surrendered a winning position to go down 3-2 against Barclays Premier League opposition at the weekend, and boss Billy Davies made five changes to his XI from the side who started at West Ham - left-back Paul Konchesky making his Reds debut following his loan switch from Merseyside.
A bright opening to proceedings set the pattern for the first half as Gary McSheffrey clipped the crossbar with a 25-yard free-kick and Marcus Tudgay almost caught out Westwood from a similar distance.
Hot-shot McGugan soon mis-cued from inside the area before Moussi snatched a first-time volley straight at Westwood, yet such was the nature of the first half it was no surprise to see Coventry break the deadlock in the 26th minute.
McSheffrey whipped in a cross from the left which King and Freddy Eastwood combined to send over the line.
However it took merely five minutes for McGugan to level matters as his shot from distance bounced in front of Westwood and deceived the Republic of Ireland stopper, who was left red-faced.
And it was quickly 2-1 courtesy of a bizarre Forest second.
Moussi surged down the right before feeling his hamstring suddenly go yet, with Coventry's defence having stopped, the Frenchman managed to whip in a cross which Earnshaw duly finished from 12 yards.
Moussi's next move was to be replaced by Paul McKenna as the visitors preserved their narrow advantage until half-time.
And Coventry suffered further injury woe at the break as Clingan's replacement Nathan Cameron was also forced off, youngster Jordan Clarke coming on.
But they should have been level in the 57th minute when Eastwood glanced King's cross wide of target from six yards.
The hosts continued to search for a leveller in the second half, however goalscoring opportunities were not as forthcoming at either end as they were in the opening 45 minutes.
Lukas Jutkiewicz found the side netting in the 79th minute as Coventry pressed but it was all to no avail as high-flying Forest withstood the pressure.