Sublime place-kicking from out-half Rhys Patchell kept Cardiff in contention for much of the contest, and the hosts required a late penalty try before they eventually secured a morale-boosting triumph.
Cardiff registered an impressive 11 tries in their opening round win against Zebre, and when you consider that the Leinster line remained unbreached for the duration of the action, Cullen praised defensive coach Kurt McQuilkin for his efforts.
“Kurt is working the guys really hard with the defence. The fact that we were able to keep hold of the ball more this week than we did last week takes a bit of pressure off our defence,” Cullen remarked afterwards. “Kurt will be delighted with the efforts that the guys put in.”
Either side of a missed penalty by Isa Nacewa ( playing in Ballsbridge for the first time since resuming his Leinster career), Patchell twice found his range from the kicking tee.
Yet, Nacewa eventually opened the home account with a 14th minute three-pointer, and Jack Conan subsequently powered over the Cardiff line for a converted score. Their Welsh counterparts played with great resilience, though, and another outstanding long-range Patchell penalty left the bare minimum (10-9) between the teams at the break.
A routine close-range Nacewa place-kick restored Leinster’s four-point advantage six minutes after the restart, but owing to a six-point haul by Patchell, the prospect of a second successive defeat became a possibility for the 2013/14 champions heading into the final-quarter.
Flanker and man of the match Josh Van Der Flier (one of several young players to be given an opportunity by Cullen in the absence of 17 World Cup-bound stars) was beginning to exert his influence, however, and after strong work had provided the platform for a third Nacewa penalty, relentless play towards the Blues’ line led to referee Ben Whitehouse awarding the decisive penalty try three minutes from the end.
J Conan try, penalty try, I Nacewa 3 pens, 2 cons.
R Patchell 5 pens.
I Nacewa; F McFadden, B Te’o, N Reid, G Ringrose; C Marsh, L McGrath; M Bent, A Dundon, J Hagan; R Molony, M McCarthy; D Ryan, J Van Der Flier, J Conan.
D Leavy for Ryan (44-49, blood sub), R Burke-Flynn for Hagan (47), I Boss for McGrath (55), B Byrne for Dundon (58), C Kelleher for McFadden (60), Leavy for Van Der Flier, Peter Dooley for Bent (both 75), Tadhg Beirne for McCarthy (76).
D Fish; A Summerhil, T Isaacs, G Evans, O Jenkins; R Patchell, T Knoyle; S Hobbs, K Dacey, C Mitchell; J Hoeata, J Down; J Turnbull, J Navidi, M Vosawai.
E Jenkins for Vosawai (h-t), L Reed for Down (67), T Davies for Hobbs, S Andrews for Mitchell (both 69), L Jones for Knoyle (70), G Smith for Jenkins (78).
B Whitehouse (WRU).