Leinster brought Cardiff Blues' Magners League home record to an end with a 30-19 bonus-point victory at Cardiff Arms Park on Friday.
Leinster took time to realise that the match was there for the taking but handed out a lesson in finishing which brought them a deserved bonus point.
The Blues, with the confidence generated by three wins to start the season, threw the ball around from the start and a break by fly-half Nicky Robinson deserved a try, only for centre Dafydd Hewitt to be held up over the line.
Leinster took the lead with a long-range penalty by Jonathan Saxton after Blues skipper Xavier Rush was guilty of a high tackle, before the home side were denied again when wing Tom James was bundled into the corner flag.
The Irish province were relying mainly on fairly aimless kicks downfield, but one bore fruit when Ben Blair and Robinson each failed to deal with it and sustained Leinster pressure ended with Christian Warner floating out a long pass for wing Luke Fitzgerald to touch down.
Blair made amends with a searing break from his own half, earning the position for Mark Lewis to go over out wide.
Sexton restored the Leinster lead with another penalty from near halfway which glanced off a post.
The Blues' frustration continued with Jamie Roberts knocking on in the act of scoring following a Robinson cross kick, and the fly-half was wide with a penalty to end the half.
Leinster began the second period with more belief and their back row, with Jamie Heaslip and replacement Stephen Keogh prominent, began to test the home defence.
They were rewarded when Fitzgerald was first to reach a kick by Sexton and cross for a try which its architect converted.
Two Robinson penalties narrowed the gap before Scottish referee Peter Allan finally tired of Leinster's ball-killing antics and yellow-carded centre Fergus McFadden.
Yet it was Leinster who scored next. An interception by hooker Bernard Jakman left him faced with 80-yards of empty field. He covered 50 of them before being overhauled, but the move continued and Heaslip crashed over.
Making light of their numerical disadvantage, Leinster claimed their fourth try when Sexton found his way in near the flag and then added the extras.
The visitors suffered a second sin-binning - this time for prop Stan Wright - and Blues wing James added a late try, but it provided no consolation.
Tries: Lewis, James
Pens: Robinson 3
Tries: Fitzgerald 2, Heaslip, Sexton
Cons: Sexton 2
Pens: Sexton 2
Yellow Card: Fergus McFadden (57th minute - Leinster), Stan Wright (76th minute - Leinster)
Cardiff Blues: 15 Ben Blair, 14 Jamie Roberts, 13 Tal Selley, 12 Dafydd Hewitt, 11 Tom James, 10 Nick Robinson, 9 Jason Spice, 8 Xavier Rush (c), 7 Robin Sowden-Taylor, 6 Mark Lewis, 5 Paul Tito, 4 Robert Sidoli, 3 Gary Powell, 2 Gareth Williams, 1 John Yapp.
Replacements: 16 Scott Roberts, 17 Ross Johnson, 18 Bradley Davies, 19 Scott Morgan, 20 Richie Rees, 21 Dai Flanagan, 22 Tom Riley.
Leinster: 15 Rob Kearney, 14 Gary Brown, 13 Fergus McFadden, 12 Christian Warner, 11 Luke Fitzgerald, 10 Jonathan Sexton, 9 Chris Whitaker, 8 Jamie Heaslip, 7 Shane Jennings, 6 Kevin McLaughlin, 5 Leo Cullen (c), 4 Trevor Hogan, 3 Stephen Knoop, 2 Bernard Jackman, 1 Stan Wright.
Rep lacements: 16 Brian Blaney, 17 Cian Healy / Juan Francisco Gomez, 18 Cameron Jowitt, 19 Stephen Keogh, 20 Keith Gleeson, 21 Cillian Willis, 22 Ross McCarron.
Venue: Cardiff Arms Park
Referee: Peter Allen
Touch judges: Gwyn Morris, Mike Bethell