Leinster coach Leo Cullen said the manner in which Leinster's young players carved out a hard-earned victory at the RDS was a source of great encouragement.
einster, with 17 players away on World Cup duty, have been stretched more than any other side and were under some pressure to deliver having lost away to Edinburgh on the opening weekend.
But, in a game where Garry Ringrose became the latest to make his debut and 22-year old Josh van der Flier captured the man of the match award in his third start, Leinster's young guns showed there is plenty to be optimistic about.
They should, of course, have eased their way to victory much more smoothly but giving away penalties at this level will prove costly and that is one of the many lessons learned from this Pro12 encounter.
"It is great to be up and running," said Cullen after his first competitive home match in charge. "A little bit of good and bad in the performance, I thought we started pretty well, showed good intent with our attack. The lads showed good composure to come back from being behind in the last 15 minutes."
Rhys Patchell, who could only manage one of eight attempts at goal in their landslide opening win over Zebre, kicked five from five on Saturday, including three monster kicks.
But Leinster pressure yielded a 17th minute try from hard-working No.8 Jack Conan as Cullen's troops, with van der Flier superb, bossed things up front while further back Ben Te'o (left) put in a great shift.
The home side led 10-9 at half-time and Isa Nacewa, who hit two from four in the first half, extended the lead shortly after the restart. However, Leinster lost their way after that and Patchell edged Cardiff back in front before the home pack took over and Nacewa landed another penalty.
They went for the jugular in the closing minutes, opting for the corner with a kickable penalty and were rewarded with a penalty try after Cardiff skipper Josh Navidi was binned.
Cullen said that far from lamenting the loss of so many players to the World Cup, he sees it as a great chance for others to come through.
"It is a great opportunity. We had Garry Ringrose out there for his first cap. Tadhg Beirne came off the bench for his first cap. Ross Molony and Cathal Marsh - their first starts here in the RDS. We had a couple of new caps last week as well.
"This is a great period for us where we get to work with some younger players. It is great experience for those guys. Particularly being in that situation where they are behind with 15 minutes to go and they dig a result out of the bag. We are very pleased, there are plenty of things that we can work on for sure, but some pleasing signs."
Leinster - I Nacewa; G Ringrose, B Te'o, N Reid, F McFadden (C Kelleher 59); C Marsh, L McGrath (I Boss 52); M Bent (P Dooley 74), A Dundon (B Byrne 56), J Hagan (R Burke-Flynn 48); R Molony, M McCarthy (T Beirne 75); D Ryan, J van der Flier (D Leavy 74), J Conan.
cardiff -D Fish; A Summerhill, T Isaacs, G Evans, O Jenkins (G Smith 78); R Patchell, T Knoyle (L Jones 70); S Hobbs (T Davies 69), K Dacey, C Mitchell (S Andrews 69); J Hoeata, J Down (L Reed 67); J Turnbull, J Navidi, M Vosawai (E Jenkins 40).
ref - B Whitehouse (WRU)