Junior Hoilett’s 12th minute goal has given Cardiff City a 1-0 lead over the Blues at half-time at the Cardiff City Stadium.
Town boss Mick McCarthy made six changes to the side which beat Burton Albion 2-1 on Saturday.
Into the XI came Bersant Celina, Dominic Iorfa, Tommy Smith, who was making his first appearance since the opening day of the campaign, Flynn Downes, Grant Ward and Kevin Bru, who was handed his first start of the season.
Adam Webster, Martyn Waghorn, David McGoldrick, Jordan Spence and Freddie Sears were all rested - Town have three games in eight days - and dropped to the bench, while Tristan Nydam was missing from the 18.
The Blues started in a 4-1-2-3 system with Downes and Bru, who came on as a sub against the Brewers, just ahead of Cole Skuse in central midfield, Ward and Celina in the wide roles and Joe Garner the lone central striker.
Cardiff were without striker Kenneth Zohore and midfielder Aron Gunnarsson due to ankle injuries and full-back Joe Bennett, who has a calf problem.
The Bluebirds made three changes from the team which drew 0-0 with Millwall at the weekend with Lee Tomlin, Omar Bogle and Callum Paterson coming into the team for Craig Bryson, Town summer target Danny Ward - who both dropped to the bench - and the injured Bennett.
Former Blues keeper Brian Murphy and ex-loan winger Liam Feeney were both among the Cardiff subs.
The Bluebirds made the early running, Sol Bamba hooking over following a long Paterson throw, then home skipper Sean Morrison claimed he was hauled back by Garner as a corner came over from the left. The former Reading man may have had a case.
On seven Hoilett struck the game’s first serious effort, cutting in from the left before shooting across Bartosz Bialkowski’s goal and wide.
Town were still to get going when the Bluebirds took the lead in the 12th minute. Nathaniel Mendez-Laing was given plenty of time to cross deep from the right and an unmarked Hoilett hit a rather scuffed volley into the ground and past the unsighted Bialkowski. It was a goal which appeared all too easy for the home side to score.
Having gone behind the Blues began to make some headway, Bru seeing a strike from the edge of the area blocked.
But on 16 Cardiff would have doubled their lead but for a brilliant Bialkowski stop. Hoilett curled across a teasing low ball from the right, which Bogle toed towards goal only for the Blues’ Polish keeper to stick out a foot and keep it out.
In the 27th minute Celina was rather less successful with a freekick from just outside the area than he had been at the weekend, hitting his strike straight at the wall after Downes had been fouled as he broke towards the box after good work from the Kosovo international in the build-up.
The Blues were beginning to pass the ball with more confidence and in the 31st minute they should have got on terms.
Celina sent over a corner which had been well won by Ward from the right, Garner rose highest to flick across goal straight to Smith at the far post, who scraped wide when he should have scored.
Chambers blocked a Bogle overhead kick inside the area with his head on 38, before Cardiff keeper Neil Etheridge badly mis-kicked when out of his goal on the Cardiff right. Fortunately for the home side Ward was unable to find space to shoot at the empty goal.
The Bluebirds had another chance a minute later when Mendez-Laing was fed in behind Smith but the former Rochdale man smashed into the side-netting.
Town carved out another opportunity to equalise in the 40th minute, Celina weaving his way into the box before finding Downes unmarked on the right of the area. The 18-year-old looked destined to score his first senior goal but somehow Joe Ralls slid in to divert the ball behind.
The Blues again weren’t too far away from a leveller in the 44th minute, Garner rising high to head Celina’s left-sided corner over the bar.
In first-half injury time Ralls hit a shot from the edge of the Town box which was deflected behind after a well-worked Cardiff counter-attack.
The scoreline remained the same at the break, the Blues having come more into the game as the half wore on having made a slow start during which they conceded Cardiff’s goal.
They might well have conceded again before creating but being unable to take two or three chances to equalise. However, the Bluebirds continued to be a threat at the other end.
Cardiff: Etheridge, Peltier, Morrison (c), Ecuele Manga, Tomlin, Ralls, Bamba, Paterson, Mendez-Laing, Bogle, Hoilett. Subs: Murphy, Ward, Feeney, Halford, Damour, Bryson, Gounongbe.
Town: Bialkowski, Iorfa, Knudsen, Chambers (c), T Smith, Skuse, Downes, Bru, Celina, Ward, Garner. Subs: Gerken, Webster, Waghorn, McGoldrick, Spence, Connolly, Sears. Referee: Oliver Langford (West Midlands).