|Blues (9) 9|
|Pens: Patchell 3|
|Ulster (12) 26|
|Tries: Tuohy, Humphreys|
|Cons: Jackson, Humphreys|
|Pens: Jackson 4|
Dan Tuohy scored his third try in three Pro12 games as Ulster maintained their unbeaten start to the season with victory away to Cardiff Blues.
The match had been delicately poised after a physical first half that had seen Paddy Jackson kick Ulster into a 12-9 lead.
Rhys Patchell had kept Blues in touch with three of his own penalties.
But lock Tuohy surged through the Blues' midfield, before Ian Humphreys' interception try sealed it for Ulster.
Unfortunately for Tuohy, the nine-times capped Ireland player was forced off 20 minutes from the end with a worrying forearm injury.
Blues had kept Ulster at bay in the first half with some impressive defence work, with a head-on tackle by Sam Hobbs on Robbie Diack particularly eye-catching.
The home side had opted to rest Wales captain Sam Warburton for the match, with Josh Turnbull and Josh Navidi taking the flanker roles.
Alex Cuthbert and Patchell, selected at full-back rather than his usual fly-half spot, created chances for Blues but they were unable to fashion a clear scoring opportunity against an organised Ulster side.
The visitors opted not to commit too many men to the breakdown in defence, spreading their numbers to choke space out wide and picking their moments to pounce when a Blues ball-carrier got isolated.
Any chances to score which came via referee Neil Paterson's whistle were all converted into points by Jackson and Patchell, with both men on target with every kick they took in the first period.
That sequence ended after half-time as Patchell missed a chance to bring Blues level and Jackson then blotting his copybook with an effort that fell just short.
But with 51 minutes on the board, Ulster drove into the hosts' 22, sucking in defenders to allow Tuohy to hit the open-side at pace, handing off a despairing dive from Matthew Rees to go under the posts for a converted try.
Blues almost hit straight back as Patchell made progress down the left before feeding Richard Smith, only for the winger to drop the ball - perhaps with one eye on the cover defence surging across.
Ulster sealed the win when replacement Humphreys picked off Gareth Davies's long pass to lope away, converting the score himself to hand Blues their second home loss in a row after their 12-33 defeat against Glasgow.
Cardiff Blues: Rhys Patchell; Alex Cuthbert, Adam Thomas, Gavin Evans, Richard Smith; Gareth Davies, Lewis Jones; Sam Hobbs, Matthew Rees (capt), Adam Jones, Jarrad Hoeata, Filo Paulo, Josh Turnbull, Josh Navidi, Manoa Vosawai
Replacements: Rhys Williams, Taufa'ao Filise, Scott Andrews, Macauley Cook, Ellis Jenkins, Lloyd Williams, Cory Allen, Geraint Walsh
Ulster: Louis Ludik; Andrew Trimble, Darren Cave, Stuart Olding, Tommy Bowe; Paddy Jackson, Paul Marshall; Andrew Warwick, Rory Best (capt), Wiehahn Herbst; Dan Tuohy, Franco van der Merwe; Robbie Diack, Chris Henry, Nick Williams.
Replacements: Rob Herring, Callum Black, Bronson Ross, Neil McComb, Roger Wilson, Michael Heaney, Ian Humphreys, Craig Gilroy.
Referee: Neil Paterson (SRU)
Assistant Referees: Leighton Hodges, Jon Mason (both WRU)
Citing Commissioner: Denis Jones (WRU)
TMO: Gareth Simmonds (WRU)