Leinster held off a second-half fightback from Ospreys to win 19-16 and maintain their 100 per cent home record in this season's Pro12.
The Irish side, who are second in the table, held a comfortable 16-3 lead by half-time at the RDS Arena, but Ospreys outscored the hosts 13-3 in the second period in a valiant attempt to overturn the deficit.
Dan Leavy scored the only try of the first half when Fergus McFadden made the break well into Ospreys' territory and the forward was on his shoulder in support to cross.
Ian Madigan added the extras before firing a further three penalties in the 20 minutes leading up to half-time, leaving the visitors an major task.
But Ospreys refused to back down and, after a period of sustained pressure, Dan Baker's quick feet saw him hit the gap from close range on the hour mark, with Sam Davies adding the extras.
Madigan's trusty boot once again stretched Leinster's lead and, although Davies brought the scores back to within three points, the hosts held firm for the win.
There was further Irish success over Wales on Saturday as Munster defeated Dragons 26-5 at Thomond Park.
Prop David Kilcoyne scored two of Munster's four tries, Rory Scannell and James Cronin the others.