Blues full-back Dan Fish goes over at the corner flag against Leinster
Dan Fish scored the only try of the game to help Cardiff Blues climb over Leinster to claim second place in the Magners League table.
After Ceri Sweeney had put the Blues ahead with an 18th-minute penalty Fish went over in the right corner, the full-back beating the cover to score.
Leinster full-back Isa Nacewa struck a penalty just before half-time to reduce the deficit to 8-3 at the break.
Crucially Sweeney kicked a late penalty to deny Leinster a losing bonus point.
The Blues showed commendable enterprise from the start, spreading the ball wide at every opportunity.
But it was Leinster who created the first clear-cut scoring chance, only for centre Eoin O'Malley to hurl his pass out of the reach of unmarked winger Niall Morris and into touch.
At the other end, Blues speedster Richard Mustoe almost sneaked in on the right but could not prevent a foot landing on the touchline.
It was a penalty by Sweeney which put the Blues in front but they spurned further efforts, preferring to go for the close range line-out.
Mustoe was held up just short and number eight Xavier Rush lost the ball forward as he dived for the line.
Young relieved after 'tough' win
But the Blues' adventure was finally rewarded when veteran flanker Martyn Williams popped up as a link man on the blind side of a ruck and put full-back Fish in at the flag for an unconverted try.
Leinster came back in the closing seconds of the first half, full-back Nacewa, who had missed two earlier attempts, slotting over a straightforward penalty.
Encouraged, the Irish stepped up the pace after the break, lively fly-half Ian McKinley being foiled by a last-ditch tackle from home scrum-half Tom Slater, before the visiting pack drove across the line but were unable to ground the ball.
The Blues soon regained control, however, with flanker Andries Pretorius increasingly prominent, and Williams darted over only to be called back for a forward pass by Sweeney.
The Welsh side maintained their pressure but were unable to turn territory into points and their lead only survived when Leinster wasted a simple try opportunity.
Nacewa switched direction to send Andrew Conway galloping into the Blues' 22 but the winger's final pass went to ground with the line at the mercy of flanker Dominic Ryan.
The inevitable substitutions disrupted the flow but the introduction of Cook Islands prop Stan Wright, making his first appearance since injuring an Achilles in August, brought new stability to a previously vulnerable Leinster scrum.
Sweeney was just off target with a penalty from halfway but when he had another shot from wide out, the former Wales international curled the ball inside the far post to clinch the home side's victory.
Blues: Dan Fish; Richard Mustoe; Gavin Evans, Dafydd Hewitt, Tom James; Ceri Sweeney, Tom Slater; John Yapp, Gareth Williams, Fau Filise, Deiniol Jones, Paul Tito (capt), Andries Pretorius, Martyn Williams, Xavier Rush. Replacements: Rhys Williams; Sam Hobbs, Scott Andrews for Filise (55), Ben White, Ma'ama Molitika for Rush (60), Rhys Downes for Slater (77), Dan Parks, James Loxton for James (64).
Leinster: I Nacewa, A Conway, E O'Malley, E Sheridan, N Morris, I McKinley, I Boss; H van der Merwe, R Strauss, C Newland, L Cullen (capt), D Toner, K McLaughlin, D Ryan, R Ruddock. Replacements: J Harris-Wright for Strauss (77), J McGrath, S Wright for Newland (58), N Hines for Toner (58), S Keogh for R. Ruddock (64), E Reddan for Sheridan (49), I Madigan for McKinley (58), M Keating for Morris (67).
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.