Tommy Miller's penalty just after the hour mark was enough to give the Blues a hard-fought win at Cardiff's Ninian Park. Miller had won the spotkick himself, spinning inside the Bluebirds' box and Danny Gabbidon sending him tumbling.
The Blues continued with the 3-5-2 formation which had proved so successful against Nottingham Forest, Jim Magilton's absence with a tear to his calf the only change. Darren Currie deputised as he had in the second half on Saturday. Frenchman Jimmy Juan was on the bench for the first time.
The home side had the first chance of the game, Chris Barker crossing from the left and Lee Bullock heading over the bar.
On six there was a scare for the Blues when Cameron Jerome went in late on Kelvin Davis. Fortunately the keeper was OK to carry on after composing himself.
Five minutes later, Richard Naylor did well to head a right-wing Richard Langley cross from under the cross bar.
Jerome should have done better after getting behind Richard Naylor in the 16th minute, but put his shot wide of the on-rushing Kelvin Davis and also the post. Had he scored Town might have had complaints that the youngster had fouled Naylor.
Town's first serious chance of the game fell to David Unsworth. The loanee latched onto a deep Darren Currie corner but hit his shot straight to keeper Neil Alexander.
Soon after, a Richard Langley freekick from wide on the left missed everyone in the box and rather fortunately flew past the post.
Town gradually got on top of the game and the very wet conditions - it rained constantly for the first half hour - and in the 34th minute Darren Bent cut in from the left and struck a curling shot which Alexander gathered.
Two minutes later, Ian Westlake exchanged a one-two with Shefki Kuqi on the edge of the area before shooting low, hard and wide.
The Blues ought to have gone ahead in the 37th minute. Matt Richards played the ball into the box from the left to Shefki Kuqi who worked himself a chance. The Finnish international shot goalwards but Alexander had rushed off his line to block.
Richard Langley hit a 20-yard freekick into a Town wall in the 38th minute. From the subsequent corner Kelvin Davis failed to get much on a punch but the ball was eventually cleared.
Town had enjoyed the better of the first half without often testing the Cardiff keeper. The home side had had their moments and Gabbidon and Collins looked solid at the back but appeared lacking in attack.
The Blues started the second half as they had ended the first but failed to eke out too many opportunities. In the 53rd minute Junichi Inamoto picked up the first yellow card of the game for a series of fouls on Darren Currie.
Two minutes later Fabian Wilnis came close to his first goal of the season when he rode a number of tackles before hitting a shot which deflected through to Alexander.
Within a minute, Darren Currie had a shot deflected over the bar, Jason De Vos heading the resultant corner to the keeper. In the 57th minute, Town boss Joe Royle switched Shefki Kuqi with James Scowcroft.
Just before the hour mark Darren Currie unleashed a stunning 30 yarder which went just over the bar. Had it gone in it would have been the Town goal of the season.
However, the goal the Blues deserved wasn't too much longer in coming. Miller turned Gabbidon inside the box and the Welsh international brought him down. There seemed little doubt and Miller hit the spotkick low and hard to Alexander's left and into the net for his 12th goal of the season.
On 64 Jobi McAnuff became the second Cardiff player to be shown a yellow card when he fouled Ian Westlake.
A minute later a weak Jason De Vos header fell to Langley on the Cardiff right. The midfielder played the ball into the middle to McAnuff but the former West Ham man shot straight at Kelvin Davis.
Darren Bent drove straight to Alexander in the 68th minute but three minutes later had the ball in the net having beaten the keeper to a ball in the air. However, referee Olivier took heed of a linesman who felt the England U21 international had fouled the goalkeeper.
With 12 minutes remaining, Cardiff sub Toni Koskela sent in a freekick from deep which Bullock put over the bar.
The Bluebirds came closest to an equaliser in the 83rd minute when Danny Gabbidon shot just over from the edge of the area.
With four minutes of normal time left, an increasingly defensive Town swapped Darren Bent for Kevin Horlock. Despite some pressure from the home side, the Blues came through unscathed - a Richard Naylor yellow card for timewasting aside - and gained their second win in four days.
Not the rampaging performance of Saturday but a solid away display and a fully deserved win. Conditions didn't always help the Blues pass the ball around but they played the better football against a Cardiff side who rarely looked like threatening Kelvin Davis.
Comfortable wins for Sunderland and Wigan keep Town in third place but, with those two sides still to meet one another and the Black Cats yet to visit Portman Road, the situation at the top remains too close to call.
Town: Davis, Wilnis, Unsworth, De Vos, Naylor, Richards, Miller, Currie, Westlake, Bent (Horlock 86), Kuqi (Scowcroft 57)