Forest boss Billy Davies said: "We played some wonderful football, created a lot of chances and thoroughly deserved to take three points.
"The game was a great advert for Championship football and, in my opinion, Cardiff are a little bit ahead of us in terms of their development but there were so many good things about us today.
"We had 24 hours less than Cardiff to prepare for the game but we looked bright and fit and showed great character and spirit.
"Our back five as a unit were superb and I was disappointed for them that we conceded a goal from a penalty that should never have been. I'm going to have a moan and I have seen a replay of it and it was never a penalty.
"The lads at the back deserved a clean sheet but the important thing was that we won the game.
"Yes, we've gone second in the table but it's just another three points in a long, hard season. The players know there is a lot of hard work to be done over the last 15 games and we will just keep working hard and see where it gets us.
"As I keep on saying, we are good candidates for a play-off spot."
Cardiff counterpart Dave Jones felt his team did enough to take something from the match.
The defeat brought the Bluebirds' seven-match unbeaten run to an end and Jones said: "It was a pretty open game and we felt we should have got something from the game - it was frustrating.
"We certainly shouldn't have gone in at half-time 1-0 down. We started very well and after the first 20 minutes we could have been at least two goals to the good.
"In the end the game could have gone either way. Goals change games and perhaps we didn't have the composure that was required to make the most of the situations we created.
"We got back into it with a penalty that looked a bit harsh from where I was standing but at that time I thought we deserved to be back in it.
"After that we had a couple of more chances that the keeper has made great saves.
"We could have dealt with both their goals before they ended in our net and the last person we wanted to see in that area for them in a goalscoring position for the winner was Earnie (Robert Earnshaw).
"But we will lick our winds and get ready to go again on Tuesday and try and get back on track."
"There will be a lot of twists and turns in this division before the season is over - there are probably 10 teams up there with not a lot between us. I will be surprised if the top two that are there will be the top two at the end."