Ulster struggled in Llanelli last time out and they disappointed again here in Cardiff, where they have only won once before back in 2005.

Some assured place-kicking from New Zealander Ben Blair set the Blues on the way to a 9-3 half-time lead, and with Ryan Caldwell and Darren Cave dispatched to the sin-bin, Cardiff struck for the only try of a tightly-contested game.

Ma'ama Molitika, who had been introduced just four minutes earlier, touched down off a 64th minute lineout drive, with Blair adding the conversion.

Ulster fly-half Niall O'Connor hit back with his third penalty from four attempts, but Blair, celebrating his 31st birthday, had the final say as he took his kicking contribution to 14 points.

It was Cardiff's second victory in five league games and although his side never hit top gear, Blues boss David Young was just pleased to get the points in the bag.

"It was a bit of a nail biter but we're just happy to get the win," he said.

"It wasn't a classic and probably wasn't great entertainment to watch but points are more important at the moment.

"You could see we were a little edgy, we spilled a lot of ball and we didn't play that well."

Both sides were boosted by the return of international players from Six Nations duty, and while individual errors and penalties did little for the game's flow, there was enough for the 7,532-strong crowd to get their teeth into.

Cardiff drew first blood in the 11th minute when tricky centre Casey Laulala carried forward into the Ulster 22, referee Neil Paterson awarded a penalty for hands in the ruck and Blair landed the kick.

Ulster's well-drilled defence kept the hosts at arm's length and their solid set piece saw them grow into the game. Blair missed his second shot at the posts soon after, and O'Connor punished the Blues for an offside with a long range effort in the 20th minute.

With the sides level, Ulster briefly seized the initiative but O'Connor failed to find the target with his second penalty attempt, as Cardiff captain Paul Tito was pinged for not rolling away after the tackle.

The Blues livened things up on the half hour mark when Blair built from the back with some evasive, angled running.

Tito and Rhys Thomas linked well in midfield as Cardiff sensed a score, but strong tackling from Simon Danielli and Cave saw Ulster keep the hosts out with Martyn Williams held up short of the try-line.

The try did not come as Young's charges kept pressing close to half-time, and they had to settle for two more penalties from Blair to take a 9-3 advantage into the break.

Cardiff continued to take the game to Ulster on the restart but the visitors thwarted a number of attacks and produced some key turnovers, before O'Connor fired over a morale-boosting, monster penalty for his side, with half-an-hour remaining.

Leigh Halfpenny and Blair failed to convert penalty efforts, either side of Caldwell's sin-binning for hands in the ruck.

The Blues pack got on the front foot again and worked a penalty for their Kiwi full-back, but Blair's shot clipped the post and the scoreline remained delicately poised at 9-6.

The game's defining moments came at the start of the final quarter as Cave saw yellow for a trip on Halfpenny in midfield, putting Ulster down to 13 men and under a serious amount of pressure.

Cardiff immediately took advantage, kicking the penalty to touch and a well-executed lineout assault saw Molitika muscle over for the all-important try, which Blair converted.

Molitika then went close to adding a second try as the Blues went for the kill.

And while a collapsed scrum allowed Ulster, with Cave still in the sin-bin, close the gap with O'Connor's third penalty, Blair cancelled that out with the last of his haul.

The sides will meet again next Saturday at Ravenhill, where Cardiff will be hoping to record their seventh straight win over the Ulstermen.