Sam Warburton's return was not enough to stop Cardiff Blues slipping to a bonus-point defeat to Pro12 champions Leinster.
The victorious British and Irish Lions skipper played his first game since a hamstring injury ruled him out of the third Test win against Australia.
Returning Lion Brian O'Driscoll had a hand in one of Leinster's four tries.
Blues wing Alex Cuthbert and replacement centre Cory Allen crossed for tries.
While centre O'Driscoll and number eight Jamie Heaslip were also making their first starts since being the Lions tour in the summer, it was fly-half Ian Madigan who was a constant threat for Leinster.
He finished the game with a try and a personal tally of 19 point, with hooker Sean Cronin and Dominic Ryan crossing for tries and the home side being awarded a controversial penalty try.
This was a much improved performance from the Blues after becoming the first side to be beaten by Italian side Zebre in the Pro12.
On their last two visits to Dublin to face Leinster, the Blues had been on the end of two 50 point drubbings.
The visitors started well with a dominant ten-minute spell but all they had to show for all their pressure and endeavour was solitary Halfpenny penalty.
While Leinster's first attack saw them demonstrate the clinical finishing the Blues had lacked when centre O'Driscoll delivered a deft pass to put hooker Cronin over for a try which was converted by Madigan.
Madigan added two more penalties before Halfpenny converted his second penalty to make it 13-6 at the break.
Leinster then benefited from two controversial decisions by Italian referee Marius Mitrea which changed the complexion of the game.
He sin-binned lock Filo Paulo for hands in the ruck, leaving the Blues down a man, and then awarded Leinster a penalty try at the resulting scrum to give the home side a 14-point lead.
But the visitors reply was decisive with Wales and Lions wing Cuthbert running in a superb solo effort from the halfway line, which Halfpenny converted, to haul the 14-man Blues back to within seven points.
The home side responded with a third try by flanker Dominic Ryan after the Leinster pack the splintered the Blues defence with a driving lineout from short-range.
Madigan then crossed for his try for Leinster before replacement centre Allen scored for the Blues.
Leinster: Rob Kearney; Fergus McFadden, Brian O'Driscoll, Noel Reid, Dave Kearney; Ian Madigan, Isaac Boss; Cian Healy, Sean Cronin, Martin Moore; Devin Toner, Quinn Roux; Rhys Ruddock, Dominic Ryan, Jamie Heaslip (capt).
Replacements: Aaron Dundon, Jack McGrath, Mike Ross, Tom Denton, Jordi Murphy, John Cooney, Jimmy Gopperth, Brendan Macken.
Cardiff Blues: Leigh Halfpenny; Alex Cuthbert, Owen Williams, Dafydd Hewitt, Harry Robinson; Rhys Patchell, Lloyd Williams; Sam Hobbs, Matthew Rees (capt), Taufa'ao Filise, Lou Reed, Filo Paulo, Josh Navidi, Sam Warburton, Andries Pretorius.
Replacements: Kristian Dacey, Thomas Davies, Scott Andrews, James Down, Robin Copeland, Lewis Jones, Gareth Davies, Cory Allen.
Referee: Marius Mitrea (Italy)
Assistant referees: M Patton, B O'Connell (both IRFU)
Citing commissioner: Murray Whyte (IRFU)
TMO: Alan Rogan (IRFU)