A losing bonus point will be scant consolation for the Ulstermen, keen to stay within touching distance of the top third of the table, with now only seven league matches remaining before the end of the season.

Despite having enjoyed an early eight-point lead and playing the better rugby for the first half hour at Cardiff Arms Park, a high penalty count caught up with Ulster in the second period and the Blues ran out deserving victors in the end.

Ulster spent the majority of the first 10 minutes in Cardiff territory, playing attractive attacking rugby, but crucially infringing inside the hosts' 22 on several occasions when they looked to have made a breakthrough.

However, with the Blues penalised for illegally blocking Ulster tackles on ball carrier Ben Blair, Ruan Pienaar stepped up in the 12th minute to kick the first points of the contest.

Then Robbie Diack, enjoying a good run in the team in the absence of Stephen Ferris and Pedrie Wannenburg, did his own claim to be seen as a first choice back rower no harm whatsoever by grounding his second runaway try in as many weeks.

An overthrown Cardiff lineout saw the giant South African hack forward from outside the 22. He managed to outstrip the Cardiff half-backs and touch down.

Pienaar failed to add the extras but Brian McLaughlin's men were 8-0 to the good at the end of the first quarter.

Dan Parks opened the Cardiff account moments later with a penalty, but as possession then swung in their favour for a good 15 minutes, the Welshmen displayed a distinct lack of invention, and barely threatened to breach the visitors' defence.

Indeed, Ulster were next to score, thanks to another Pienaar penalty, after poor decision making from both Parks and Gavin Henson had almost landed the Blues in very hot water.

Parks made amends in the final minute of the half with a well-struck penalty, keeping his side in touch at only 11-6 as the sides ran off at the break.

Cardiff made the best possible start to the second period, Parks scooting over in the 42nd minute after a good surge down the right wing from Blair.

The former Scotland international failed to convert but parity had been restored and with the wind at their backs, the Welsh region were hopeful of bossing the remainder of the clash.

However, Ulster swiftly showed exactly what they are capable of, a sublime Paddy Wallace dummy in midfield scything open the Cardiff defence in the 48th minute.

A try looked a distinct possibility as Wallace found Pienaar but just as the scrum half fed Craig Gilroy on the right wing, the Cardiff chasers got back well to crowd out the youngster.

Parks' erratic evening continued as his attempted clearance was charged down metres from the try-line by Wallace, but the bounce was kind to the Blues out-half, who was able to collect and clear sufficiently at the second attempt.

Play then spilled down to the other end of the pitch, and Tom James was on hand to exploit a gap in the Ulster defence and score a try after being set up by Henson. Parks converted to make it 18-11 to the home side.

An intentional knock forward saw Ian Humphreys sin-binned in the 65th minute and although Parks missed the resultant penalty, he split the posts three minutes later from further out after John Afoa had been pulled up for infringing at the scrum.

Pienaar reduced the gap back down to seven points thanks to a 71st minute penalty, but any hopes of a late Ulster fightback were quashed as Cardiff did well to close out the match in midfield.