Kieffer Moore scored his first goals for Cardiff since joining from Wigan to pile the misery on Sabri Lamouchi and Nottingham Forest as the visitors won 2-0 at the City Ground.
The Wales forward opened the scoring inside three minutes with a towering header from Marlon Pack's corner and added a second late on in the first half with a predatory finish from Sean Morrison's knock-down.
It was another frustrating afternoon for Forest, who despite being much improved in the second half could not find a way past an inspired Alex Smithies in goal, with Lewis Grabban and Ryan Yates missing their best chances.
The result means Cardiff have collected their first points of the campaign while Forest suffered their third straight loss and are winless in their previous nine games stretching back to last season.
Cardiff pile early problems on Forest
Cardiff spent £2m to sign Moore from Wigan following their demotion to League One and the 28-year-old opened his account for his new club with a trademark finish, rising high above his marker Tobias Figueiredo to power a header into the net.
While the Cardiff striker was clinical in front of goal, Forest's main attacking threat Grabban was not as he passed up a huge chance to equalise, volleying an effort high over the crossbar after being found at the back post by Luke Freeman's searching cross.
Lamouchi was clearly unhappy at what he had seen from his side in the opening stages as he summoned Lyle Taylor from the bench after 35 minutes to replace Joe Lolley in a tactical switch. The move failed to pay off as Moore added his second goal just five minutes later from close range.
Forest rallied in the second half and went close to pulling one back with 53 minutes played when Yates' header into the turf bounced up and forced Smithies into an acrobatic stop. Similarly to Grabban before him, Yates will feel he should've scored.
Grabban was denied by Smithies again after his volley from close-range was blocked by the onrushing Cardiff goalkeeper, while the hosts felt that they should have had a penalty when Jack Colback went to ground after a tangle of legs with Joe Ralls.
Forest's improvement was evidenced by the fact that they out-shot Cardiff ten to one in the second period but their final effort - a wasteful strike from Taylor that flew over the top in stoppage time - epitomised their profligacy in front of goal and Neil Harris' side were ultimately deserving of their win.
Man of the match - Kieffer Moore
Although Cardiff struggled to make much headway in attack against a much-improved Nottingham Forest in the second half, they managed to get the job done in the first courtesy of Moore's clinical finishing. Wales' No 9 finished both of the chances that fell his way and might have had an assist another day after Joe Ralls miscontrolled his cute ball into the box when through on goal.
What the managers said...
Nottingham Forest's Sabri Lamouchi: The second half was much better but it was not really difficult to play much better. We started the game in the wrong way, the first corner, the first throw in, two things we worked on all week because we know the quality of this team and the first corner we miss the marking and it is just unacceptable.
Cardiff City's Neil Harris: We didn't start great against Sheffield Wednesday, we were the better team but didn't win the game and I just said to the boys it was about our focus and mentality. Today I asked for quality in the final third which we had and for clean sheet mentality which we had for the majority of the game. I think for the first 45 minutes you saw a dominant, quality display.
Nottingham Forest are next in action on Friday as they travel to The John Smith's Stadium to face Huddersfield Town, live on Sky Sports Football. Cardiff, meanwhile, host Reading at the Cardiff City Stadium on Saturday.