Full-back Ludik scored a try in either half to supplement finishes from Craig Gilroy and Paul Marshall as the hosts picked up what could prove to be a very valuable try bonus point.

Tom Isaacs and Alex Cuthbert crossed for the Blues as they showed real resilience after the break, but the 18-0 half-time deficit ultimately proved too much.

Glasgow Warriors' draw at Leinster means Neil Doak's side stay second, but they will be pleased to have forged a bit of a buffer between themselves and the chasing pack.

Ulster burst into action from the first whistle, Stuart Olding making the first of a new number of powerful carries by the home side in a sustained attack, before Paddy Jackson's clinical miss pass allowed Gilroy to run the score in for his seventh GUINNESS PRO12 try in six matches.

Ruan Pienaar slotted the conversion to ensure the hosts led 7-0 before their Welsh visitors had even touched the ball, although the Kingspan hysteria was dampened somewhat by the sight of Olding being stretchered from the field with a serious looking leg injury.

Nick Williams was sent to the sin-bin for making illegal contact with the head of Rhys Patchell at a breakdown, an incident which led to a long break in play and ended with the Cardiff full-back carried off in a neck brace.

The visitors reacted well to that extensive stoppage, but when they turned down an eminently kickable penalty, Pienaar punished the profligacy with a three-pointer of his own, stretching the score to 10-0 before Ulster registered their second try of the night.

The hosts initiated an irresistible driving maul, and when the ball was recycled, Jackson fed Ludik, who bustled his way through three tackles and stretched for the score - Pienaar wayward with the conversion.

Cardiff had won their previous two GUINNESS PRO12 matches in a belated assault on the top six, but they were struggling to get a foothold in this match as the first half wore on, Pienaar again on target from the tee with a penalty to make it 18-0 after 31 minutes.

And although Franco van der Merwe became the second Ulsterman to see yellow before the break, Cardiff couldn't cross their opponents' whitewash after countless phases, Cuthbert's decisive offload drifting forward as Cory Allen looked to finish.

Ulster had won four league matches on the bounce before a surprise 26-22 defeat at Newport Gwent Dragons last time out, and Pienaar's penalty straight after half-time enforced the notion that they were to their best at the Kingspan.

Gareth Anscombe then slotted a three-pointer of his own from in front of the posts to register his side's first score, before replacement Isaacs grabbed a try.

Argentina international Lucas Amorosino was the architect, waltzing through the white shirted defence and offloading to Anscombe, who sent Isaacs in unimpeded.

That score seemed to set the game alight, with both sides finding gaps and playing some dynamic running rugby.

The electric atmosphere built to a crescendo when Ulster flanker Chris Henry, who suffered a mini-stroke in November, made his Kingspan return from the replacements bench.

But that uproar was soon silenced, Cuthbert crossing the hosts' line after another period of incessant pressure by the Blues. Anscombe converted again, and suddenly Ulster's lead was a slender one at 21-17.

Another Pienaar penalty gave Doak's side a little breathing space, but it was not until Ludik gathered a picture perfect Ian Humphreys cross-field kick to score in the right corner that the home faithful could begin to celebrate the success.

Marshall then gathered well to run home a breakaway score for the hosts that brought up the precious bonus point, securing a fifth GUINNESS PRO12 win in six in the process to maintain Ulster's designs on a home semi-final.