It was late heartbreak for City, as a late strike saw the hosts, Bolton Wanderers, take all three points on Saturday afternoon.
Brian Barry-Murphy made five changes to the side that beat Reading at Cardiff City Stadium last time out with Will Fish, Dylan Lawlor, Isaak Davies and Perry Ng joined in the starting XI by Alex Robertson, making his first appearance of the competitive campaign.
It was a tense match from the opening. Both sides have big aspirations this season and neither wanted to give their opposition any opportunities, and it showed.
The returning Robertson struck from distance 12 minutes in but he failed to test Teddy Sharman-Lowe in the Bolton Wanderers goal. A minute later, top goalscorer for the hosts, Mason Burstow, took his chance to shoot from outside the box, but it similarly went wide of goal.
City's best chance of the opening 45 came from David Turnbull, who headed off target inside the box from Joel Bagan's cross. Dangerman Burstow had the best chance for the hosts, sweeping wide from close range 33 minutes in.
The game somewhat lacked high octane goalmouth action with the two teams battling it out in the middle of the park to best each other.
Brian looked to his bench to find the magical spark with Tanatswa Nyakuhwa, Cian Ashford, Ronan Kpakio, Ryan Wintle and Callum Robinson introduced.
It looked like the points would be shared until the final minute of added time when winger Amario Cozier-Duberry produced a moment of magic from distance to secure the win for the hosts.
For the Bluebirds, it is a break from league action for the next two fixtures, starting in the Carabao Cup Fourth Round on Tuesday at Wrexham.
FINAL SCORE: BOLTON WANDERERS 1-0 CARDIFF CITY
Bolton Wanderers: Sharman-Lowe, Dacres-Cogley, Simons (Morley 88'), Johnston, Sheehan, Osei-Tutu, Toal, Cozier-Duberry, Forss (Dalby 65'), Conway (Taylor 75'), Burstow (Randall 75'). Subs Not Used: Miller, Forino, Cissoko.
Cardiff City: Trott, Ng, Lawlor, Fish, Bagan (Kpakio 77'), Robertson (Wintle 77'), Turnbull, R.Colwill, Kellyman (Nyakuhwa 65'), Davies (Ashford 65'), Salech (Robinson 83'). Subs Not Used: Chambers, J.Colwill.