Ulster condemned Cardiff Blues to their second loss in a row against Irish opposition as they edged a scrappy match at the Arms Park on Friday.
Blues: (12) 22:
Pen: N Robinson 5.
Ulster: (9) 25:
Pens: Humphreys 5.
A kicking battle between fly-halves David Humphreys and Nick Robinson saw the scores tied deep into the match.
But in a grandstand finish Ulster wing Tommy Bowe fielded a clever chip to race away for a try under the posts.
Humphries added a vital drop-goal to keep Ulster out of reach despite Craig Morgan's late try for the Blues.
After losing at Connacht last week, Blues coach Dai Young was hoping home advantage would help them get off the mark against Ulster.
Robinson gave the Blues an early lead after three minutes, stroking a straightforward penalty from in front of the posts after Humphreys was caught offside.
Humphreys soon replied for Ulster, but the visitors infringed directly from the restart and handed Robinson another simple kick to restore the Blues' slim lead.
After sitting out the opening weekend with a bye, Ulster were understandably playing with a certain degree of rustiness.
But the Blues' handling was little better and, one rampaging run off the base of the scrum from Andy Powell and a snipe from scrum-half Mike Phillips aside, made little headway.
Humphreys potted another penalty to level things at 6-6, rewarding Ulster's best foray at the Welsh line as new signing Justin Harrison just had his 6ft 8in frame stopped short of the line.
But despite repulsing the Australian international lock, a lack of composure attracted referee Rob Dickson's whistle once more.
Ulster again spoilt things by gifting back a penalty from the restart, which Robinson again converted.
A further Humphreys penalty predictably followed, as the game limped into its second quarter needing something to spark it into life.
Phillips at last gave the crowd something to roar on, breaking half the length of the pitch after a cheeky dummy and chipping ahead.
But Ulster centre Paul Steinmetz was alert to the threat and did well to tidy up the loose ball.
It was left to Robinson to have the last word of the half, thumping his fourth successive penalty - although he missed another in injury time - between the sticks for a 12-9 Blues lead.
A few choice words must have been said in the changing rooms, as both sides emerged with renewed enthusiasm.
Unfortunately a half-time shower of rain made conditions greasy, and the only slick thing about the handling was the moisture on the ball.
In between the drops and spills, Robinson struck his fifth penalty, while opposite number Humphreys made amends for an earlier miss with his fourth and fifth kicks to draw the scores level once more at 15-15.
Finally there came a moment of real quality, as Ulster scrum-half Kieran Campbell chipped superbly from the base of a scrum to send Bowe away to score.
Blues wing Morgan was caught completely flat-footed and Bowe had all of the field to play with as he motored around full-back Nick Macleod to score under the posts.
Humphreys added the easy conversion and then turned the screw with a drop-goal at the first opportunity to open a 25-15 lead.
With two minutes of normal time left, Blues skipper Rhys Williams burst through midfield and sent Morgan away over the whitewash.
Robinson's excellent conversion reduced Ulster's lead to just three points and set up a nail-biting finish, but the Blues had to settle for just a bonus point in defeat.
Blues coach Young was frustrated by his side's performance: "We've got to cut these silly mistakes out.
"We gave away too many silly penalties and our error count must have been massive - we just couldn't keep hold of the ball.
"There was a lack of confidence but we didn't keep the ball long enough to go wide."
Blues: Macleod; Czekaj, R Williams (capt), Davies, Morgan;
N Robinson, Phillips; Yapp, R Thomas, M Jones, Quinnell,
Sidoli, Molitika, Sowden-Taylor, A Powell.
Replacements: R Powell for Phillips (73),
Evans for M Jones (67), D Jones for Quinnell (73),
Lewis for A Powell (69).
Not Used: G. Williams, L. Thomas, Nuthall.
Ulster: Wallace; Bowe, Maggs, Steinmetz, Trimble; Humphreys,
Campbell; J Fitzpatrick, Shields, S Best (capt), Harrison,
McCullough, N Best, McMillan, Wilson.
Replacements: R Best for Shields (58),
Frost for McCullough (50).
Not Used: B. Young, Feather, Marshall, Topping, Larkin.
Referee: Rob Dickson (SRU).