Blues put to the sword by super Scarlets
Leinster 15 Scarlets 27
The Scarlets ruined a potential all-Ireland final in becoming the first club to win away from home in the PRO12 League semi-final.
In truth, Leinster got nothing more than they deserved as they were outplayed and outthought by the Welsh club, despite playing with an extra man for 43 minutes.
The Scarlets had to turn back the clock 10 years to the only time they had beaten Leinster at the RDS in order to carry out mission improbable.
They brought the form to back up their promise, losing just once in their last 11 in the PRO12.
The only problem with that was that it happened in humiliating fashion at The Showgrounds.
Leinster came to this gunfight with mass weapons at their disposal in record-breaking tries (91), record-breaking points (674), and record-breaking bonus points (12) for a single season.
The Scarlets had to start hard and fast to let Leinster know there would be no repeat of what went down in March.
It was Jonathan Sexton who made the first impact, a rattling tackle that shook the ball free from James Davies.
From there, captain Isa Nacewa was prominent in knitting together a series of phases that was stalled by referee Marius Mitrea deeming Sexton's pass to be forward as Nacewa hared away to the line.
It was either a sign of things to come or an immediate wake-up call for Scarlets.
They took it as the latter, soaking up educated pressure until Sexton, of all people, spilled the ball.
When Adam Byrne was powerless to prevent Jonathan Davies breaking, the Welsh were in behind and number eight John Barclay put Stef Evans over for the League-leading try-scorer's 12th of the season.
Rhys Patchell dispatched the conversion for 7-0 in the ninth minute just as Jack McGrath was replaced by Cian Healy.
Leinster lock Hayden Triggs took up the challenge in a power-drive, Barclay giving away the penalty.
Ireland's Garry Ringrose almost squeezed through a gap, Wales centre Davies hammered Carbery, and the ball slipped out of Triggs' fingers.
Tadhg Beirne bounced Robbie Henshaw and left wing Evans stepped Sexton only to be met by the smothering Ringrose.
It wasn't long before Sexton countered down the left and Josh van der Flier drew a penalty out of Lewis Rawlins for Nacewa to slot three in place of the shaken Sexton.
Then, Leinster's collective rush defence, led by Triggs, forced a fumble from which Luke McGrath was reeled in by wing Evans for Liam Williams to poach a try-saver.
Jamison Gibson-Park replaced McGrath and Leinster were ruthless from the subsequent lineout.
Hooker James Tracy was central to setting up Sexton to work Jack Conan into space for Ringrose to strike on the inside shoulder and Nacewa converted.
The to-and-fro continued as Aaron Shingler and Gareth Davies exchanged a one-two for the flanker to fend off Gibson-Park for Scarlets' second try and Patchell made it 14-10 in the 26th minute.
The home side was leaking like a sieve, Rhys Ruddock getting into a bad position as Scarlets rifled a third converted try from scrum-half Davies on the half hour.
Jonathan Davies' reading of the play was exceptional in the midfield and his brother James pinched a turnover to keep Leinster at arm's length.
Gareth Davies' decision to ruffle up Sexton cost Scarlets perfect position and Stef Evans mistimed tackle was Marius Mitrea's idea of a red card just before the half concluded.
Leinster returned with one more man and in need of many more points.
Sexton got isolated to cough up a penalty and Gibson-Park lashed the ball out on the full.
Devin Toner entered the contest, perhaps to confirm the Blues' necessity to become more direct.
Eventually, it took the sheer bloody-minded muscle of Tracy, Dan Leavy and, finally, Jack Conan to close the gap from close range before Nacewa uncharacteristically missed the extras in the 63rd minute.
When Healy was whistled for the second time at the scrum, Liam Williams struck from the left to make it a nine-point game with ten on the clock.
Beirne came to Scarlets rescue for a penalty turnover as Leinster went wide without going forward.
It all ended with Ross Molony's high tackle on Scott Williams for Liam Williams to make certain.