Cardiff moved seven points clear at the top of the Championship after a 1-0 victory at Birmingham, while second-placed Hull had to settle for a 0-0 draw at Blackpool on New Year’s Day.
Malky Mackay’s team took the points thanks to Joe Mason’s first-half goal and look well on course for promotion to the Premier League after several near-misses in recent years.
Mason, recalled to the Cardiff starting line-up, netted his fifth goal of the season in the 41st minute, following up to tap home from close range after Jack Butland’s parried save from Craig Conway had taken a fortuitous bounce.