Good to see you back, BOD. The shoulder operation that removed Brian O'Driscoll from this year's Six Nations' Championship – and who knows whether his presence might have stalled Wales's Grand Slam march that began with a mightily marginal victory on this ground – has done its job, and the great centre reprised some of his peerless skills in this romp.
O'Driscoll scored one try and had a big hand in Leinster's other three as the Heineken Cup holders and 2009 champions earned a fourth successive semi-final.
They will have to complete their title defence on the road: the last-four tie will be away to Saracens or Clermont Auvergne at Twickenham or Bordeaux's Stade Chaban-Delmas, three weeks today. There is a Twickenham final to play for. Munster or Ulster will "host" the other semi here at the Aviva Stadium.
While Wales's national side are doing fine, its regions – slashing playing budgets and seeing their stars take the gravy train to France – suffer shockingly by comparison with the Irish provinces. Leinster's scrum was ruthless. The first set- piece brought them a penalty and Scott Andrews, the Blues tighthead, must have known he was in for a long evening. Though the resulting line-out was stolen from Leinster's swanky All Black loan signing Brad Thorn, it merely delayed a score when Jonny Sexton, Leinster's Ireland fly-half, kicked a penalty to equalise Leigh Halfpenny's third-minute belter. It was asking a lot for the Blues to cover for five injured players, including the Wales captain, Sam Warburton, and the man of the 2009 Lions series, Jamie Roberts. There had also been the kerfuffle in the week of sacking Gavin Henson.
The scrum spelt trouble. To adapt the old Goons song, the Blues were walking backwards for Easter, over the Irish Sea.
The first Leinster opportunity to run – a tapped penalty by Sexton – brought their first try, 12 minutes in. O'Driscoll and Kevin McLaughlin scampered and Sexton shot through, dummied Halfpenny and fed Rob Kearney, who sent Isa Nacewa over. Sexton kicked the conversion, missed a penalty then converted Kearney's 30th-minute try. It originated with a scrum from a free-kick 10 metres inside Leinster's half and Eoin Reddan's break from an adroit pass by O'Driscoll.
The third of the first-half trio of tries was the best. Leo Cullen, returning from injury, batted a line-out and Jamie Heaslip fed Sexton, whose sumptuous inside ball was taken at pace by Luke Fitzgerald. The wing had O'Driscoll on his shoulder and Sexton converted for a 27-3 interval lead.
Leinster have variety and it will take a good side to prise the cup from their fingers. Two snapped passes by O'Driscoll led to a second try for Kearney after 46 minutes, with Sexton converting. Though there was no further score Thorn's juddering tackles, O'Driscoll's jackalling and the openside foraging of Shane Jennings in the last half-hour made you suspect the impressive Cardiffian spirit to keep trying was being utilised by Leinster as live defensive practice.
A chance for Martyn Williams was lost when the flanker let the ball slip over the line. Ceri Sweeney, on for Dan Parks, got almost as close with five minutes left, no more successfully. Whatever the Cardiff sobriquet might be, it was the home supporters' cries of "Come on the boys in blue" that rang true.
"The dressing room wasn't overly elated," said O'Driscoll, after the third match of his comeback from a five-month lay-off. "Good sides always pick holes in a victory. We're not getting silly about it, we are where we want to be and we'll enjoy watching Clermont and Saracens on Sunday afternoon."
The Blues captain, Xavier Rush, said: "Leinster put us under pressure at scrum-time and you figure if a good side has the number of chances they did, they'll win."
In the Amlin Challenge Cup, Biarritz beat Wasps 26-23 at Adams Park. The Scarlets, the only non-French team left, play Brive in France this evening.
Leinster R Kearney; I Nacewa, B O'Driscoll (I Madigan, 68), G D'Arcy, L Fitzgerald (F McFadden, 59); J Sexton, E Reddan (I Boss, 61); C Healy (H van der Merwe, 65), R Strauss (S Cronin, 52), M Ross (N White, 72), L Cullen (capt), B Thorn (D Toner, 59), K McLaughlin (S Jennings, 49), J Heaslip, S O'Brien.
Cardiff Blues L Halfpenny; A Cuthbert, C Laulala, D Hewitt, T James; D Parks (C Sweeney, 68), L Williams (R Rees, 68); G Jenkins, M Breeze, S Andrews, B Davies, J Down (M Molitika, 59), M Paterson, X Rush (capt), M Williams.
Referee D Pearson (England).
Tries: Nacewa, Kearney 2, O'Driscoll
Cons: Sexton 4
Pens: Sexton 2