Passion, energy, work rate, effort and plenty of good attacking football in a first half that Cardiff dominated to lead 2 - 0 at half time.
For the first time in a long time Cardiff dominated a half with solid efficiency and clinical finishing. Forest could have taken the lead when Chris Burke fired past David Marshall but Craig Noone cleared off the line and soon after City led.
Federico Macheda playing his best game for City marauded to the edge of the box and slotted his shot past Darlow in the Forest goal.
Cardiff continued to press Forest and disrupt any hope of a game plan from Stuart Pearce's side. Five minutes after Macheda's goal Peter Whittingham saw an opportunity and struck a grass cutter from just over 20 yards to increase City's lead.
Whether it was passing, tackling, tracking back or closing down the team put in a fantastic effort to make Forest look ordinary and very frustrated. Considering Forest were unbeaten this season they were second best to a side invigorated by their new manager.
it wasn't long ago that Ole Gunnar Solskjaer's side led Norwich 2 - 0 at half time before collapsing to a 4 - 2 defeat. Slade's team are made of sterner stuff though and it was only a set of substitutions that weaked City's grip on a game they fully deserved to win.
Macheda went off on the hour to be replaced by Kenwynne Jones. And from then on the flow of the game changed. Jones, possibly jet lagged from travel to the Carribean, was not as mobile as Macheda and when the industrious Aron Gunarsson was replaced by Tom Adeyemi the game plan fell apart. Adeyemi looked totally committed when he came on but last just two minutes before having to be replaced himself through injury.
Mats Moller Daehli came on and Slade pushed Craig Noone back to left back and moved Joe Rals into midfield. Ralls started at full back after Fabio was taken ill minutes before the game.
City found themselves dropping deeper as Forest plugged away. Mostly they blew their chances and were sloppy in their approach but a disallowed goal acted as a warning for City. A warning they didn't heed as in the 89th minute City were exposed in the left back position and Assombalonga stole in to convert Michail Antonio's cross.
There was a deep intake of breath as Cardiff defended four minutes of injury time before Mike Jones blew the final whistle.
The good work was done in the first half and so far all the signs are positive under the new manager.
Special mentions to Bruno Manga who was excellent in defence despite playing games in Africa in the past week, to Adam LeFondre for his constant harrying and closing down to disrupt Forest and finally to the ground staff who produced another superb pitch for the third time in 9 days after the two Wales games.
They will have to prepare the surface again as Cardiff entertain Ipswich on Tuesday. The Tractor Boys are another side in great form. Can Slade get another massive effort from his team. I'd guess he will motivate them far more than his predecessor and for that reason City have a chance.
Cardiff City: D Marshall (c), J Brayford, B Manga, S Morrison, J Ralls, P Whittingham, A Gunnarsson (T Adeyemi 66) (M Daehli 68), C Noone, A Pilkington, F Macheda (K Jones 62), A Le Fondre
Goals: Macheda 22, Whittingham 27
Nottingham Forest: K Darlow, E Lichaj (D Harding 46), M Mancienne, K Wilson, M Fryatt, B Assombalonga, H Lansbury (D Vaughan 56), J Hunt (L Vedwijk 77), M Antonio, C Burke, R Tesche
Goal: Assombalonga 89
Ref: M Jones
Att: 21,263